Topic
Substrate (chemistry)
About: Substrate (chemistry) is a research topic. Over the lifetime, 35902 publications have been published within this topic receiving 740722 citations. The topic is also known as: enzyme substrate.
Papers published on a yearly basis
Papers
More filters
01 Sep 1965
136 citations
TL;DR: The smallest of these enzymes from bovine liver, termed acid phosphatase III, has been purified to apparent homogeneity and migrates as a single band during electrophoresis on polyacrylamide gel and yields arginine as the only detectable amino terminal residue.
136 citations
TL;DR: Results indicate that the enzyme produced by a mutant of Bacillus subtilis IMR-NK1 is a subtilisin-like serine protease, similar to nattokinase from Bacillus natto.
Abstract: A mutant of Bacillus subtilis IMR-NK1, which is used for the production of domestic "natto" in Taiwan, produced high fibrinolytic enzyme activity by solid-state fermentation using wheat bran as medium. In addition, a strong fibrinolytic enzyme was purified from the cultivation media. The purified enzyme was almost homogeneous, as examined by SDS-PAGE and capillary electrophoresis. The enzyme had an optimal pH of 7.8, an optimal temperature of 55 degrees C, and a K(m) of 0.15% for fibrin hydrolysis. The molecular mass estimated by gel filtration was 31.5 kDa, and the isoelectric point estimated by isoelectric focusing electrophoresis was 8.3. The enzyme also showed activity for hydrolysis of fibrinogen, casein, and several synthetic substrates. Among the synthetic substrates, the most sensitive substrate was N-succinyl-Ala-Ala-Pro-Phe-pNA. PMSF and NBS almost completely inhibited the activity of the enzyme. These results indicate that the enzyme is a subtilisin-like serine protease, similar to nattokinase from Bacillus natto.
135 citations
TL;DR: Together, the kinetic and crystallographic data strongly suggest that both Asp189 and Gly216 must be considered as primary determinants of substrate specificity in trypsin.
Abstract: Converting the specificity of trypsin to that of chymotrypsin has been shown to require the exchange of amino acids in multiple portions of the protein, including two surface loops which do not directly contact the substrate. Crystallographic analysis of two mutant trypsins possessing chymotrypsin-like specificity now reveals that these distal surface loops alter function by directly determining the structure of the primary binding site. Efficient acylation of cognate substrates correlates with a distinct backbone conformation of the conserved Gly216 residue. This amino acid is located on the surface of the specificity pocket and forms two main-chain hydrogen bonds with a nonspecific portion of substrate. By contrast, the improvement in substrate binding affinity effect by the substitution of the distal Tyr172 residue with Trp derives from structural rearrangements at the extreme base of the pocket. Together, the kinetic and crystallographic data strongly suggest that both Asp189 and Gly216 must be considered as primary determinants of substrate specificity in trypsin.
135 citations
TL;DR: δ-Aminolevulinic acid dehydratase from Rhodopseudomonas spheroides, an enzyme which catalyzes the synthesis of the pyrrole, porphobilinogen, from 2 molecules of δ-aminolevulusic acid, has been purified 300- to 400-fold and exhibits many of the characteristics of an allosteric enzyme.
135 citations