Papers by Peramachi Palanivelu
World Journal of Advanced Research and Reviews, 2024
In eukaryotes, genome replication starts with the initiation of replication by the primases, foll... more In eukaryotes, genome replication starts with the initiation of replication by the primases, followed by the synthesis of the leading-and lagging-strands by two different replicative DNA polymerases (pols), viz. ε and δ, respectively. The polymerase and proofreading (PR) active sites of the δ pols are analyzed from various animal and plant sources by multiple sequence alignment (MSA). The animal and plant δ pols are found to possess almost identical polymerase and PR domains. However, the BLASTp analysis has shown only 56.57% identity between the plant (Arabidopsis thaliana) and animal (human) δ pols. The template-binding pair (-YG-), the catalytic amino acid (K) and the nucleotide selection amino acid (Q) are found to be the same in both plant and animal δ pols. The δ pols from plant and animal sources contain a typical Mg 2+-binding motif, (-YGDTD-) in the polymerase domain and 2 possible Zn 2+-binding motifs (ZBMs) in their carboxy terminal domain (CTD). One of the ZBMs binds to the 4Fe-4S cluster and is suggested to be involved in the regulation of replication. Interestingly, the invariant-SLYPS-and-YGDTD-motifs which are found in the δ pols are not found in the other replicative pol ε. Furthermore, both animal and plant δ pols use the same PR exonuclease active site amino acids, and thus, belong to the DEDD(Y)-superfamily of exonucleases, as found in other DNA pols. Besides, many specialized, conserved sequence motifs are also identified and discussed.
World Journal Of Advanced Research and Reviews, Jun 30, 2024
It is well-known that human immunodeficiency viruses (HIVs) cause the chronic, potentially life-t... more It is well-known that human immunodeficiency viruses (HIVs) cause the chronic, potentially life-threatening condition known as human Acquired Immuno-Deficiency Syndrome (AIDS). As the lifecycle of HIVs heavily depends on the crucial enzyme, the reverse transcriptase (RT), it has been used as a potential therapeutic target to treat and control the spread of AIDS. The active site amino acids of the polymerase domain of the RTs and their anti-HIV drug-binding sites are analyzed. The catalytic region of HIV RTs and the E. coli DNA polymerase I showed very similar active site amino acids, suggesting that HIV RTs would have possibly evolved from the bacterial DNA polymerase. The catalytic proton abstractor is identified as a K and the nucleotide selection amino acid as an N. However, the regular template-binding pair –YG- is slightly modified to a –YXG- in HIV RTs. Three completely conserved Ds in HIV RTs are involved in binding to the catalytic Mg2+. The sensitive and resistant strains of HIV-1 for the HIV antiretroviral drug, azidothymidine (AZT), a nucleoside analogue of thymidine, show only a few non-isofunctional amino acid replacements and are located mainly in the palm and thumb subdomains of the RT polymerase, whereas the rest of the polymerase catalytic core and metal-binding sites are completely conserved in AZT-sensitive and -resistant HIV-1 strains. In the drug-resistant mutants of non-nucleoside RT inhibitors of HIV-2, the crucial mutations are located mainly near the -MDD- motif of the catalytic metal-binding region. Even though a large number of amino acid replacements are seen between the RTs of HIV-1 and HIV-2, the polymerase active sites are completely conserved in both. The HIV-1 and HIV-2 catalytic and metal-binding sites are completely conserved in simian immunodeficiency virus (SIV) as well. The absence of DEDD-superfamily of proofreading exonuclease domain in the HIV RTs, might cause the virus to evolve rapidly in patients. A possible mechanism of action for the HIV RTs is also proposed.
Zenodo (CERN European Organization for Nuclear Research), Jun 29, 2023
World Journal of Advanced Research and Reviews
Mitochondria, found in all eukaryotic cells, play a crucial role in generating much needed biolog... more Mitochondria, found in all eukaryotic cells, play a crucial role in generating much needed biological energy for the cells in the form of adenosine triphosphates (ATPs). It is a semi-autonomous organelle and is partly controlled by its own genome and mostly by the nuclear imports. To replicate its own genome, it uses two DNA polymerases, viz. polymerases IA and IB which are essentially similar to the E. coli DNA polymerase I. The nuclear-encoded RNA polymerase (NEP) (EC 2.7.7.6) is imported from the nucleus and involves in the transcription of all mitochondrial genes. In Arabidopsis thaliana, the mitochondrial NEP showed 59.05% identity to the NEP of the chloroplasts, but only 28.24% identity to the T7 RNA polymerase, suggesting the NEPs of mitochondria and chloroplasts are distinctly different. However, in both the plant NEPs, the polymerase catalytic core and proofreading (PR) exonuclease domains are completely conserved. The mitochondrial NEP’s catalytic core from different plant...
World Journal of Advanced Research and Reviews, 2023
Chloroplast plays a crucial role in all photosynthetic plants and converts the light energy to ch... more Chloroplast plays a crucial role in all photosynthetic plants and converts the light energy to chemical energy. It is a semiautonomous organelle and is mostly controlled by its own genome and partly by the nuclear imports. To replicate its own genome, it uses two DNA polymerases, viz. polymerases IA and IB. DNA polymerase IA showed 72.45% identity to polymerase IB, but only 35.35% identity to the E. coli DNA polymerase I. Multiple sequence alignment (MSA) analysis have shown that the DNA polymerases IA and IB and the E. coli DNA polymerase I possess almost identical active sites for polymerization and proofreading (PR) functions, suggesting their possible common evolutionary origin. The nuclear-encoded RNA polymerase (NEP) is imported from the nucleus and involves in the transcription of all the four subunits of the chloroplast RNA polymerase. The polymerase catalytic core of the DNA polymerases IA, IB and the NEP are remarkably conserved and is in close agreement with other DNA/RNA polymerases reported already, and possess a typical template-binding pair (-YG-), a basic catalytic amino acid (K) to initiate catalysis and a basic nucleotide selection amino acid R at-4 from K. The DNA polymerases IA and IB are very similar to prokaryotic DNA polymerases, except in possessing a zinc-binding motif (ZBM) in them, like the eukaryotic replicases. Interestingly, the PR exonucleases of all three polymerases belong to the DEDD-superfamily of exonucleases. The DNA polymerases IA and IB belong to the DEDD(Y)-subfamily, whereas the NEP belongs to the DEDD(H)-subfamily.
World Journal of Advanced Research and Reviews, 2024
Recent reports have made it clear that mutations in the mitochondrial DNA (mtDNA) polymerase γ (P... more Recent reports have made it clear that mutations in the mitochondrial DNA (mtDNA) polymerase γ (POLG1) are a major cause of many human diseases. Mutations in the mtDNA polymerase leads to defective oxidative phosphorylation and ATP production, resulting in many mitochondrial diseases. For their mitochondrial genome replication, humans and animals use POLG1, whose catalytic site is essentially similar to the E. coli DNA polymerase I (DNA pol I). Multiple sequence alignment (MSA) analysis have shown that the POLG1 and E. coli DNA pol I use identical amino acids in their polymerase catalytic sites, viz.-943R-4 EHAKI 1 FNYGRI955Y 8 G-(human DNA pol γ) as-R-4 RSAKA 1 INFGLIY 8 G-(E. coli DNA pol I). However, the human POLG1 shows only 31.25% identity with the E. coli DNA pol I, suggesting a highly divergent evolution. Mutation(s) in the POLG1 gene is one of the most common causes of many inherited mitochondrial diseases in children and adults. Depending on their location within the enzyme, mutations either lead to mtDNA depletion or accumulation of multiple mtDNA deletions leading to various mitochondrial diseases. The most common POLG1 dominant mutation, viz. Y955→H/C, which lead to a severe, early-onset of multi-systemic mitochondrial disease with bilateral sensorineural hearing loss, cataract, myopathy, and liver failure is located in the template-binding pair of the polymerase catalytic site region by MSA. Another dominant mutation, R943→H/C is observed in patients with Progressive External Ophthalmoplegia (adPEO, an autosomal, dominant, heritable mitochondrial disorder) is located in the nucleoside triphosphate (NTP) selection amino acid in the polymerase catalytic site region. The nuclear-encoded RNA polymerase (NEP) is imported from the nucleus and involves in the transcription of all the mitochondrial genes. The human mitochondrial NEP showed 39.30%, 40.12% and 26.98% identities to the NEPs of the mitochondria and chloroplasts of Arabidopsis thaliana, and T7 RNA polymerase, respectively, suggesting that the human and plant mitochondrial NEPs are distinctly different. Interestingly, the human NEP's catalytic core is almost completely conserved in the plant mitochondrial and chloroplast NEPs, viz.-R-4 KVVKQ 1 TVMTVVY 8 G-(Human) and-R-4 KLVKQ 1 TVMTSVY 8 G-(A. Thaliana). Furthermore, the mitochondrial NEP's catalytic core from human and different animal sources is remarkably conserved and is in close agreement with other NEPs of plant sources. Both the human DNA pol γ and NEP possess a typical template-binding pair (-YG-), a basic catalytic amino acid (K) to initiate catalysis and a basic nucleotide selection amino acid R at-4 from the catalytic K. The PR exonucleases of POLG1 and NEP belong to the DEDD-superfamily of exonucleases and uses a Y or H as the proton acceptor, respectively.
Zenodo (CERN European Organization for Nuclear Research), Jan 30, 2023
RNA polymerase from human influenza viruses is a heterotrimeric enzyme and performs the crucial f... more RNA polymerase from human influenza viruses is a heterotrimeric enzyme and performs the crucial functions of both transcription and replication for multiplication of the viruses in human cells. The heterotrimeric enzyme is made up of two basic protein subunits (PB1 and PB2) and an acidic protein subunit (PA). All the three subunits perform welldefined function(s) in the transcription and replication processes in the human cells. The basic protein subunit PB1 is shown to possess the polymerization activity, whereas the PB2 and the PA subunits are found to be involved in the capsnatching and proofreading (PR) activities, respectively. The polymerase activity in the catalytic subunit, PB1, is found to be an RNA-dependent RNA polymerase (RdRp). Multiple sequence alignment (MSA) analysis of the PB1 subunits from all the three human influenza viruses, A, B and C shows large number of highly conserved peptides, amino acid motifs and invariant amino acids. Site-directed mutagenesis (SDM) analysis and X-ray crystallographic data have shown that two completely conserved motifs, viz.-GDN-and-SDD-, are involved in binding to the catalytic Mg 2+ ion. These data are in close agreement with the MSA analysis data of the polymerases from all the three human influenza viruses. Furthermore, two highly conserved polymerase catalytic regions are identified in the PB1 subunits by sequence similarity to other DNA/RNA polymerases and hence, are proposed to function in the nucleotidyl transfer activities. Presence of the two catalytic regions suggest that the polymerase may function in a dual mode, i.e., in phase I, in association with the cap-snatching subunit PB2, it could be involved in the synthesis of mRNAs (transcription mode) and once enough proteins are made from the mRNAs, in the second phase, in association with PR exonuclease subunit PA, it could switch to the replication mode to synthesize error-free, exact copies of the viral genome. For both the activities, it could use the same invariant catalytic Mg 2+-binding-GDN-and-SDD-motifs.
Federation Proceedings, 1981
Protein Expression and Purification, Apr 1, 2013
Keratinolytic proteases find extensive applications both in environmental biotechnology and pharm... more Keratinolytic proteases find extensive applications both in environmental biotechnology and pharmaceutical industries. An extracellular keratinolytic protease was purified and characterized from the fungus, Aspergillus parasiticus, isolated from poultry soil. The enzyme was purified to homogeneity by acetone and ammonium sulfate precipitations followed by CM-Sepharose column chromatography. The molecular mass of the enzyme was 36kDa as judged by SDS-PAGE. The purified keratinase had a pH optimum of 7.0 and temperature optimum of 50(o)C. The enzyme hydrolyzed the substrate azocasein and the Km and Vmax of the purified keratinase were found to be 1.04mg/ml and 3463.34Units/min/mg protein, respectively. The enzyme showed increased activity in the presence of reducing agents. The enzyme was found to be glycosylated. According to the inhibition profiles obtained with the various protease inhibitors, it was confirmed that the purified keratinase belongs to the serine protease type. The purified enzyme activity was enhanced by calcium, magnesium and manganese ions and partially inhibited by cadmium, copper and zinc ions. The purified enzyme showed increased activity with nonionic detergents and urea.
World Journal Of Advanced Research and Reviews, Jun 30, 2023
Human respiratory syncytial virus (hRSV) is one of the triple epidemic viruses that causes infect... more Human respiratory syncytial virus (hRSV) is one of the triple epidemic viruses that causes infections of the respiratory tract and lungs. For multiplication of the virus in human cells, its RNA polymerase is the crucial enzyme and it forms a part of a large protein (LP). The LP is a multicomponent and multifunctional protein harboring at least 3 different enzymes. The RNA polymerase belongs to RNA-dependent RNA polymerase (RdRp) (EC: 2.7.7.48) type and performs the synthesis of both mRNAs (transcription) and genomic RNA (gRNA) (replication). In addition to the RNA polymerase, the LP also harbours two more enzymes, viz. enzymes for cap addition and cap methylation of mRNAs. The polymerase domain of the LP is analyzed for its active site amino acids and its proofreading (PR) domain. Two polymerase active site regions and a DEDD-superfamily of 3'→5' PR exonuclease active site domain are identified in the polymerase region. The signature metal-binding motifs, viz.-GDNQ-and-SDD-which are commonly found in the RdRps of all the (-) strand RNA viral pathogens are also found in the hRSV RNA polymerase. The two highly conserved polymerase catalytic core regions identified by sequence similarity are in close agreement with other DNA/RNA polymerases already reported and hence, proposed to function in the nucleotidyl transfer reactions. Presence of the two catalytic regions also suggest that the polymerase may function in a dual mode, one for transcription and the other one for replication, using the same invariant catalytic Mg 2+-binding-GDNQ-and-SDD-motifs.
Indian journal of science and technology, Oct 1, 2018
IOSR Journal of Pharmacy and Biological Sciences, 2013
A chitinase gene from the thermophilic fungus, Thermomyces lanuginosus was amplified from the gen... more A chitinase gene from the thermophilic fungus, Thermomyces lanuginosus was amplified from the genomic DNA of the fungus, by PCR technique. The PCR product was cloned into pXcmkn12 vector by TA cloning technique and sequenced. The gene contained five introns and six exons. The deduced protein sequence coded for 390 amino acids and exhibited very high degree of similarity to other endochitinases of mesophilic and thermophilic fungi. The highly conserved catalytic motif, DGLDIDWEYP, suggests that it belongs to family 18 chitinases.
World Journal Of Advanced Research and Reviews, Sep 30, 2022
RNA polymerases of human influenza viruses A, B and C do not have a capping enzyme, as other RNA ... more RNA polymerases of human influenza viruses A, B and C do not have a capping enzyme, as other RNA viruses, to cap their mRNAs for translation in the host cells. So, they employ a unique 'cap-snatching' mechanism, where the mRNA cap structures are snatched from the host cell mRNAs and used as a primer to initiate its own mRNA synthesis. One of the RNA polymerase subunits, the polymerase basic protein subunit 2 (PB2), is shown to involve in the 'cap-snatching' mechanism. The active sites for the 'cap-snatching' and endonuclease by the PB2 were analyzed by multiple sequence alignment (MSA) analysis and corroborated with the results available from biochemical, site-directed mutagenesis (SDM) and X-ray crystallographic techniques. It is found that the PB2 subunit in all three human influenza viruses habours both the cap-binding motif (CBM) and a HNH/N type endonuclease domain. The CBM is aromatic amino acid rich and the HNH/N is a-DH-based endonuclease in influenza viruses A and C and a-DQ-based one in influenza virus B. The invariant H is proposed to act as a general base to initiate catalysis and the invariant first N is implicated in nucleotide binding. In addition, the nuclear localization signals were also identified in all three human influenza viruses. By sequence similarity, similar HNH/N domain are found in the RNA cleaving CRISPR-Cas13a/13b and CRISPR-Cas12a endoribonucleases. The identification of HNH/N domain in all three human influenza viruses suggests that the PB2 subunit itself could cleave the cap structures from the host cell mRNAs, which are subsequently used as primers to initiate viral mRNA synthesis. These results will facilitate the optimization of endonuclease inhibitors as potential new anti-influenza drugs, and could also help in developing new drugs for flu treatments in the future.
Biotechnology journal international, Jan 20, 2018
Aim: To analyze the most complex multi-subunit (MSU) DNA dependent RNA polymerases (RNAPs) of euk... more Aim: To analyze the most complex multi-subunit (MSU) DNA dependent RNA polymerases (RNAPs) of eukaryotic organisms and find out conserved motifs, metal binding sites and catalytic regions and propose a plausible mechanism of action for these complex eukaryotic MSU RNAPs, using yeast (Saccharomyces cerevisiae) RNAP II, as a model enzyme.
Zenodo (CERN European Organization for Nuclear Research), Mar 30, 2023
Chloroplast plays a crucial role in all photosynthetic plants and converts the light energy to ch... more Chloroplast plays a crucial role in all photosynthetic plants and converts the light energy to chemical energy. It is a semiautonomous organelle and is mostly controlled by its own genome and partly by the nuclear imports. To replicate its own genome, it uses two DNA polymerases, viz. polymerases IA and IB. DNA polymerase IA showed 72.45% identity to polymerase IB, but only 35.35% identity to the E. coli DNA polymerase I. Multiple sequence alignment (MSA) analysis have shown that the DNA polymerases IA and IB and the E. coli DNA polymerase I possess almost identical active sites for polymerization and proofreading (PR) functions, suggesting their possible common evolutionary origin. The nuclear-encoded RNA polymerase (NEP) is imported from the nucleus and involves in the transcription of all the four subunits of the chloroplast RNA polymerase. The polymerase catalytic core of the DNA polymerases IA, IB and the NEP are remarkably conserved and is in close agreement with other DNA/RNA polymerases reported already, and possess a typical template-binding pair (-YG-), a basic catalytic amino acid (K) to initiate catalysis and a basic nucleotide selection amino acid R at-4 from K. The DNA polymerases IA and IB are very similar to prokaryotic DNA polymerases, except in possessing a zinc-binding motif (ZBM) in them, like the eukaryotic replicases. Interestingly, the PR exonucleases of all three polymerases belong to the DEDD-superfamily of exonucleases. The DNA polymerases IA and IB belong to the DEDD(Y)-subfamily, whereas the NEP belongs to the DEDD(H)-subfamily.
International Journal of Biochemistry Research and Review, Jan 10, 2013
Aim: To analyze the active sites of various prokaryotic and eukaryotic DNA polymerases and propos... more Aim: To analyze the active sites of various prokaryotic and eukaryotic DNA polymerases and propose a plausible mechanism of action for the polymerases with the Escherichia coli DNA polymerase I as a model system. Study Design: Bioinformatics, Biochemical and X-ray crystallographic data were analyzed. Place and Duration of Study: Department of Molecular Microbiology, School of Biotechnology, Madurai Kamaraj University, Madurai – 625 021, India. From 2007 to 2012. Methodology: The advanced version of T-COFFEE was used to analyze both prokaryotic and eukaryotic DNA polymerase sequences. Along with this bioinformatics data, X-ray crystallographic and biochemical data were used to confirm the possible amino acids in the active sites of different types of polymerases from various sources. Results: Multiple sequence analyses of various polymerases from different sources show only a few highly conserved motifs among these enzymes except eukaryotic epsilon polymerases where a large number of highly conserved sequences are found. Possible catalytic/active site regions in all these polymerases show a highly conserved catalytic amino acid K/R and the YG/A pair. A distance conservation is also observed between the active sites. Furthermore, two highly conserved Ds and DXD motifs are also observed. Conclusion: The highly conserved amino acid K/R acts as the proton abstractor in catalysis and the YG/A pair acts as a “steric gate” in selection of only dNTPS for polymerization reactions. The two highly conserved Ds act as the “charge shielder” of dNTPs and orient the Research Article International Journal of Biochemistry Research & Review, 3(3): 206-247, 2013 207 alpha phosphate of incoming dNTPs to the 3’-OH end of the growing primer.
Co-induction of sucrose transport and invertase activities in a thermophilic fungus, Thermomyces ... more Co-induction of sucrose transport and invertase activities in a thermophilic fungus, Thermomyces lanuginosus
Zenodo (CERN European Organization for Nuclear Research), Sep 30, 2022
RNA polymerases of human influenza viruses A, B and C do not have a capping enzyme, as other RNA ... more RNA polymerases of human influenza viruses A, B and C do not have a capping enzyme, as other RNA viruses, to cap their mRNAs for translation in the host cells. So, they employ a unique 'cap-snatching' mechanism, where the mRNA cap structures are snatched from the host cell mRNAs and used as a primer to initiate its own mRNA synthesis. One of the RNA polymerase subunits, the polymerase basic protein subunit 2 (PB2), is shown to involve in the 'cap-snatching' mechanism. The active sites for the 'cap-snatching' and endonuclease by the PB2 were analyzed by multiple sequence alignment (MSA) analysis and corroborated with the results available from biochemical, site-directed mutagenesis (SDM) and X-ray crystallographic techniques. It is found that the PB2 subunit in all three human influenza viruses habours both the cap-binding motif (CBM) and a HNH/N type endonuclease domain. The CBM is aromatic amino acid rich and the HNH/N is a-DH-based endonuclease in influenza viruses A and C and a-DQ-based one in influenza virus B. The invariant H is proposed to act as a general base to initiate catalysis and the invariant first N is implicated in nucleotide binding. In addition, the nuclear localization signals were also identified in all three human influenza viruses. By sequence similarity, similar HNH/N domain are found in the RNA cleaving CRISPR-Cas13a/13b and CRISPR-Cas12a endoribonucleases. The identification of HNH/N domain in all three human influenza viruses suggests that the PB2 subunit itself could cleave the cap structures from the host cell mRNAs, which are subsequently used as primers to initiate viral mRNA synthesis. These results will facilitate the optimization of endonuclease inhibitors as potential new anti-influenza drugs, and could also help in developing new drugs for flu treatments in the future.
Archives of Microbiology, 1983
Invertase (/~-D-fructofuranosidase, EC 3.2.1.26) activity
appeared in cultures and mycelial susp... more Invertase (/~-D-fructofuranosidase, EC 3.2.1.26) activity
appeared in cultures and mycelial suspensions of a
thermophilic fungus. Thermomyces lanuginosus, only when
sucrose or raffinose was added as the carbon source to the
medium. The enzyme activity disappeared rapidly following
the exhaustion of sugar in the culture medium. Extracellular
invertase activity was not detected. The maximal enzyme
activity occurred prior to the maximal growth of the fungus.
The appearance of invertase activity was dependent on
growth. The enzyme activity was not stable in cell-free
extracts of mycelia. The lability of the enzyme was also
observed in mycelia incubated in the presence of cycloheximide.
In the above respects the behaviour of invertase in T.
lanuginosus differs from invertase of yeasts and molds
(mesophiles) which have been studied.
World Journal of Advanced Research and Reviews
Chloroplast plays a crucial role in all photosynthetic plants and converts the light energy to ch... more Chloroplast plays a crucial role in all photosynthetic plants and converts the light energy to chemical energy. It is a semi-autonomous organelle and is mostly controlled by its own genome and partly by the nuclear imports. To replicate its own genome, it uses two DNA polymerases, viz. polymerases IA and IB. DNA polymerase IA showed 72.45% identity to polymerase IB, but only 35.35% identity to the E. coli DNA polymerase I. Multiple sequence alignment (MSA) analysis have shown that the DNA polymerases IA and IB and the E. coli DNA polymerase I possess almost identical active sites for polymerization and proofreading (PR) functions, suggesting their possible common evolutionary origin. The nuclear-encoded RNA polymerase (NEP) is imported from the nucleus and involves in the transcription of all the four subunits of the chloroplast RNA polymerase. The polymerase catalytic core of the DNA polymerases IA, IB and the NEP are remarkably conserved and is in close agreement with other DNA/RN...
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Papers by Peramachi Palanivelu
appeared in cultures and mycelial suspensions of a
thermophilic fungus. Thermomyces lanuginosus, only when
sucrose or raffinose was added as the carbon source to the
medium. The enzyme activity disappeared rapidly following
the exhaustion of sugar in the culture medium. Extracellular
invertase activity was not detected. The maximal enzyme
activity occurred prior to the maximal growth of the fungus.
The appearance of invertase activity was dependent on
growth. The enzyme activity was not stable in cell-free
extracts of mycelia. The lability of the enzyme was also
observed in mycelia incubated in the presence of cycloheximide.
In the above respects the behaviour of invertase in T.
lanuginosus differs from invertase of yeasts and molds
(mesophiles) which have been studied.
appeared in cultures and mycelial suspensions of a
thermophilic fungus. Thermomyces lanuginosus, only when
sucrose or raffinose was added as the carbon source to the
medium. The enzyme activity disappeared rapidly following
the exhaustion of sugar in the culture medium. Extracellular
invertase activity was not detected. The maximal enzyme
activity occurred prior to the maximal growth of the fungus.
The appearance of invertase activity was dependent on
growth. The enzyme activity was not stable in cell-free
extracts of mycelia. The lability of the enzyme was also
observed in mycelia incubated in the presence of cycloheximide.
In the above respects the behaviour of invertase in T.
lanuginosus differs from invertase of yeasts and molds
(mesophiles) which have been studied.