Biomaterial Database

Physical studies on assimilatory nitrate reductase from Chlorella vulgaris. 1979

L Giri, and C S Ramadoss

Assimilatory nitrate reductase (EC 1.6.6.1 NADH:nitrate oxidoreductase) from Chlorella vulgaris purified by affinity chromatography was found to be homogeneous as judged by electrophoresis on sodium dodecyl sulfate-polyacrylamide gel and by analytical ultracentrifugal techniques. The molecular weight of the intact enzyme and that of the enzyme dissociated in 6 M GuHCl, determined by sedimentation equilibrium studies, were 280,000 +/- 10,000 and 90,000 +/- 5,000, respectively. Comparable values were obtained using the S20,w value and the D20,w values in Svedberg's equation. The D20,w values were determined by laser light-scattering measurements. Active enzyme centrifugation showed that the monomer is an active species. A quantitative re-evaluation of the prosthetic groups present (FAD, heme, and molybdenum) was also made and was consistent with the conclusion that the active monomer contains three subunits as previously deduced by Solomonson et al. ((1975) J. Biol. Chem. 250, 4120). Electron micrographs showed images which corresponded to three subunits, supporting the data obtained by hydrodynamic studies. The enzyme is not cigar-shaped, as previously surmised, but has a roughly globular structure.

UI	MeSH Term	Description	Entries
D008854	Microscopy, Electron	Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.	Electron Microscopy
D008958	Models, Molecular	Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.	Molecular Models,Model, Molecular,Molecular Model
D008970	Molecular Weight	The sum of the weight of all the atoms in a molecule.	Molecular Weights,Weight, Molecular,Weights, Molecular
D009565	Nitrate Reductases	Oxidoreductases that are specific for the reduction of NITRATES.	Reductases, Nitrate
D010446	Peptide Fragments	Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.	Peptide Fragment,Fragment, Peptide,Fragments, Peptide
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D002708	Chlorella	Nonmotile unicellular green algae potentially valuable as a source of high-grade protein and B-complex vitamins.	Chlorellas
D000596	Amino Acids	Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.	Amino Acid,Acid, Amino,Acids, Amino
D013053	Spectrophotometry	The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
D014357	Trypsin	A serine endopeptidase that is formed from TRYPSINOGEN in the pancreas. It is converted into its active form by ENTEROPEPTIDASE in the small intestine. It catalyzes hydrolysis of the carboxyl group of either arginine or lysine. EC 3.4.21.4.	Tripcellim,Trypure,beta-Trypsin,beta Trypsin