Papers by Jens Sommer-Knudsen
Molecular Biotechnology, Dec 1, 1997
This article describes a quick and easy method for determining relative binding affinities betwee... more This article describes a quick and easy method for determining relative binding affinities between proteins and metal ions. The method is based on separating unbound metal ions from metal ions bound to protein by ultrafiltration using microcentrifuge ultrafiltration units. Bovine serum albumin (BSA) was used as the test protein and the relative affinity towards divalent metal ions was found to be Cu2+ > Zn2+ > Cd2+ > Pb2+ > Ni2+ > Co2+, which corresponds to the relative orders reported in the literature.
Plant Journal, 1996
A basic, galactose-rich style glycoprotein (GaRSGP) encoded by a previously characterized style-s... more A basic, galactose-rich style glycoprotein (GaRSGP) encoded by a previously characterized style-specific cDNA (NaPRP4) has been isolated from the styles of Nicotiana alata and structurally characterized. The glycoprotein is associated with cell walls in the transmitting tract and is composed of approximately 25% (w/w) protein and 75% (w/w) carbohydrate. The purified glycoprotein appears as a smear of between 45-120 kDa on SDS-PAGE; the deglycosylated protein backbone has an apparent molecular weight of approximately 30 kDa. The glycoprotein is rich in the amino acids lysine, proline, and hydroxyproline and in the monosaccharides galactose and arabinose. It is one of only a few proline/hydroxyproline-rich glycoproteins (P/HRGPs) to be characterized both as a cDNA-clone and protein. Glycans are attached to the protein backbone through both O- and N-glycosidic linkages with the majority of the carbohydrate being O-linked and consisting of short, highly branched chains terminating primarily in galactose residues. A carbohydrate epitope(s) is found on both GaRSGP and another style-specific glycoprotein but not on glycoproteins from other tissues. This finding provides further evidence for the existence of a style-specific carbohydrate epitope(s) which may play a role in style function.
Plant Molecular Biology, Dec 1, 1994
A cDNA clone, pBH72-F1 (F1), was isolated from a cDNA library prepared from barley leaves 72 h af... more A cDNA clone, pBH72-F1 (F1), was isolated from a cDNA library prepared from barley leaves 72 h after inoculation with Erysiphe graminis f.sp. hordei. The 1388 bp nucleotide sequence of pBH72-F1 contains an open reading frame encoding a 42.3 kDa polypeptide of 390 amino acids which shows sequence similarity to O-methyltransferases (OMTs) from different plant species; the highest identity (41 ~o) was observed with a putative OMT expressed in roots of maize. A phylogenetic analysis shows that the barley and maize sequences are distinctly different from the ortho-diphenol-OMTs involved in lignin formation. A putative S-adenosyl-L-methionine-binding motif (KELVDDSITN) determined for a rabbit protein-carboxyl OMT is partially conserved in the encoded amino acid sequence. Genomic Southern blot hybridization shows that pBH72-F1 probably represents a single copy gene. The F1 clone corresponds to a gene transcript exhibiting a relatively late accumulation in mildew-infected barley leaves compared to other pathogen-induced transcripts, such as transcripts encoding PR proteins, a peroxidase, and transcripts homologous to a maize caffeic acid OMT. No transcript was detected in plants exhibiting papilla resistance at time points when resistance is thought to be manifested. The atypical transcript accumulation pattern for F1 was also observed after infection by other pathogens and after UV-light treatment.
Molecular Plant-microbe Interactions, 1994
Partial amino acid sequences of two proteins, purified from barley leaves reacting hypersensitive... more Partial amino acid sequences of two proteins, purified from barley leaves reacting hypersensitively to the powdery mildew fungus, showed a high degree of amino acid identity to the PR-1 proteins originally described in tobacco. The proteins, subsequently designated HvPR-1a and HvPR-1b, show apparent pI values of approximately 10.5 and 11, respectively and apparent M(r) 15,000. Independently, differential screening of a cDNA library prepared from barley leaves, exhibiting a compatible interaction with the powdery mildew fungus, resulted in isolation of cDNA species representing two PR-1 homologs. With the exception of one amino acid, the partial amino acid sequences of HvPR-1a and HvPR-1b are identical to internal sequences of the polypeptides derived from the two cDNA species. These derived polypeptides are each 164 amino acids long and both have putative N-terminal leader sequences of 24 amino acids. That these proposed leader sequences are functional is indicated by the observed occurrence of both proteins in the intercellular fluid. The proposed mature proteins (calculated M(r) 14,490 and 15,204) share 91% identical amino acids with each other and 56 to 74% with other PR-1 proteins. Northern blot hybridization and immunoblotting, respectively, show that both transcripts and both proteins accumulate following inoculation of susceptible and hypersensitivity resistant barley leaves with the powdery mildew fungus.
Electrophoresis, 2003
Poly(vinyl alcohol) hydrogels: Their synthesis and steps towards control of electroendosmosis Pol... more Poly(vinyl alcohol) hydrogels: Their synthesis and steps towards control of electroendosmosis Poly(vinyl alcohol) (PVAl) hydrogel networks cross-linked with glutaraldehyde were prepared and their properties as membranes examined using a variety of techniques including preparative electrophoresis. Electroendosmosis (EEO) was observed and shown to be the result of charges on the membrane and of complexation with borate buffer ions. Investigation of "glutaraldehyde" solutions showed acid entities in, or formed in "glutaraldehyde" were responsible for EEO. Techniques for using "glutaraldehyde" which minimize EEO are described.
Sexual plant reproduction, Oct 2, 1997
This review summarises information on hydroxyproline-rich glycoproteins (HRGPs) and clones encodi... more This review summarises information on hydroxyproline-rich glycoproteins (HRGPs) and clones encoding these molecules isolated from male and female tissues of flowering plants. HRGPs are abundant in sexual tissues and a number of different HRGPs have been isolated. The protein and carbohydrate components of these HRGPs have been characterised and cDNAs encoding the protein backbones of several have been isolated and sequenced. Further work is directed at detailed structural analysis of the carbohydrate side chains of these molecules and their points of linkage to the protein backbones. The biological functions of most of these molecules have not yet been established unequivocally.
Phytochemistry, Feb 1, 1998
This review summarizes the structures of the four major groups of hydroxyproline-rich glycoprotei... more This review summarizes the structures of the four major groups of hydroxyproline-rich glycoproteins from plants; extensins, proline/hydroxyproline-rich glycoproteins, arabinogalactan-proteins, and solanaceous lectins. Similarities and differences within and between the groups are discussed.
Heart, Lung and Circulation, 2016
Functional Plant Biology, 2002
Throughout the world, over 400 species of plants are known to accumulate large quantities of meta... more Throughout the world, over 400 species of plants are known to accumulate large quantities of metals in their shoots (`hyperaccumulators'), but of these, relatively few accumulate manganese (Mn). We have identified for the first time an Australian native hyperaccumulator of Mn, Austromyrtus bidwillii (Benth.) Burrett (Myrtaceae). Concentrations of Mn up to 19 200 µg g-1 were measured in dried leaves of this rainforest tree, and young bark was found to contain up to 26 500 µg g-1 Mn. Approximately 40% of the Mn in the leaves is readily extracted with water, suggesting that some of the Mn is associated with water-soluble compounds such as organic acids. Organic acids present in appreciable amounts in leaf extracts of A. bidwillii were identified and quantified by HPLC and gas chromatography-mass spectrometry. The following organic acids (in order of concentration) were present: succinic > malic ≥ malonic > oxalic >> citric acid. The concentration of total organic acids ...
L'invention concerne une matrice d'affinite comprenant une matrice de base contenant de l... more L'invention concerne une matrice d'affinite comprenant une matrice de base contenant de la biotine; et une proteine de fusion fixee a la matrice de base, la fusion de proteine contenant un element de liaison de la matrice capable de se lier a la matrice de base via la biotine et un element de liaison cible capable de se lier a au moins un composant cible ou d'etre lie par ce dernier.
The Plant Journal, 1996
A basic, galactose-rich style glycoprotein (GaRSGP) encoded by a previously characterized style-s... more A basic, galactose-rich style glycoprotein (GaRSGP) encoded by a previously characterized style-specific cDNA (NaPRP4) has been isolated from the styles of Nicotiana alata and structurally characterized. The glycoprotein is associated with cell walls in the transmitting tract and is composed of approximately 25% (w/w) protein and 75% (w/w) carbohydrate. The purified glycoprotein appears as a smear of between 45-120 kDa on SDS-PAGE; the deglycosylated protein backbone has an apparent molecular weight of approximately 30 kDa. The glycoprotein is rich in the amino acids lysine, proline, and hydroxyproline and in the monosaccharides galactose and arabinose. It is one of only a few proline/hydroxyproline-rich glycoproteins (P/HRGPs) to be characterized both as a cDNA-clone and protein. Glycans are attached to the protein backbone through both O- and N-glycosidic linkages with the majority of the carbohydrate being O-linked and consisting of short, highly branched chains terminating primarily in galactose residues. A carbohydrate epitope(s) is found on both GaRSGP and another style-specific glycoprotein but not on glycoproteins from other tissues. This finding provides further evidence for the existence of a style-specific carbohydrate epitope(s) which may play a role in style function.
Molecular plant-microbe interactions : MPMI, 1994
Partial amino acid sequences of two proteins, purified from barley leaves reacting hypersensitive... more Partial amino acid sequences of two proteins, purified from barley leaves reacting hypersensitively to the powdery mildew fungus, showed a high degree of amino acid identity to the PR-1 proteins originally described in tobacco. The proteins, subsequently designated HvPR-1a and HvPR-1b, show apparent pI values of approximately 10.5 and 11, respectively and apparent M(r) 15,000. Independently, differential screening of a cDNA library prepared from barley leaves, exhibiting a compatible interaction with the powdery mildew fungus, resulted in isolation of cDNA species representing two PR-1 homologs. With the exception of one amino acid, the partial amino acid sequences of HvPR-1a and HvPR-1b are identical to internal sequences of the polypeptides derived from the two cDNA species. These derived polypeptides are each 164 amino acids long and both have putative N-terminal leader sequences of 24 amino acids. That these proposed leader sequences are functional is indicated by the observed o...
Heart, Lung and Circulation
This paper is intended to give a historical account of the work on arabinogalactan-proteins (AGPs... more This paper is intended to give a historical account of the work on arabinogalactan-proteins (AGPs) that came from our research group between 1975 and 1998. Although some work of others is mentioned, the paper is not a comprehensive review. For a more extensive discussion of the subject, the reader is referred to Clarke et al (1979), Fincher et al (1983), Knox (1995), Du et al (1996a), Nothnagel (1997), Sommer-Knudsen et al (1998) and Schultz et al (1998).
Any consideration of the structural classes of arabinogalactan-proteins (AGPs) also raises the qu... more Any consideration of the structural classes of arabinogalactan-proteins (AGPs) also raises the question, “What is an AGP?” The AGPs belong to the Hyp-rich glycoprotein (HRGP) family of molecules that also includes the extensins, Pro/Hyp-rich glycoproteins (P/HRGPs) and the solanaceous lectins (Showalter 1993, Kieliszewski and Lamport 1994, Du et al 1996a, Sommer-Knudsen et al 1998). In general, three criteria have defined AGPs: the presence of arabinogalactan chains, a Hyp-rich protein backbone and the ability to bind to a class of synthetic phenylazo dyes, the β-glycosyl Yariv et al 1962, Clarke et al 1979, Fincher et al 1983). It may now be necessary to reconsider our definitions. Arabinogalactan chains are found on proteins that do not bind the Yariv reagent [e.g., AG-peptide from wheat (Fincher et al 1974) and two glycoproteins from styles (Lind et al 1994, Sommer-Knudsen et al 1996)]. Some AGPs are Hyp-deficient, and others have short oligoarabinosides previously thought to be characteristic of the extensins and solanaceous lectins (Qi et al 1991, Baldwin et al 1993). This degree of variability is similar to that observed in glycosylation and protein backbones of the animal extracellular matrix (ECM) proteoglycans (Hardingham and Fosang 1992, Verma and Davidson 1994). These general criteria easily distinguish AGPs from the extensins and solanaceous lectins, but the boundaries between AGPs and P/HRGPs are less clearly defined. This variability raises several issues: (1) Are the criteria outlined above sufficient? (2) The AGPs are a family of molecules with different protein backbones, each existing as multiple glycoforms. Is there a distinct boundary between AGPs and P/HRGPs, or is the HRGP family a continuum of molecules? (3) Can the knowledge and experiences from the animal proteoglycan field provide additional criteria that would clarify our definitions?
Bulletin OILB …, 1993
-The efficiency of induced resistance under practical culture conditions. 5. Powdery mildew and g... more -The efficiency of induced resistance under practical culture conditions. 5. Powdery mildew and grain yield of winter and spring barley in relation to nitrogen fertilization by Oerke, E.-C.(Hannover Univ.(Germany, FR). Inst. fuer Pflanzenkrankheiten und Pflanzenschutz); ...
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Papers by Jens Sommer-Knudsen