26698-64-6

Upstream product

• 63-91-2 L-phenylalanine 
• 2224-52-4 L-alanine N-carboxyanhydride 
• 3061-90-3 L-alanyl-L-phenylalanine 
• 61043-41-2 H-Ala-Ala-Phe-p-nirtoanilide 

Relevant academic research and scientific papers

Purification and characterization of a novel extracellular tripeptidyl peptidase from Rhizopus oligosporus

A novel extracellular tripeptidyl peptidase (TPP) was homogenously purified from the culture supernatant of Rhizopus oligosporus by sequential fast protein liquid chromatography. The purified enzyme was a 136.5 kDa dimer composed of identical subunits. The effects of inhibitors and metal ions indicated that TPP is a metallo- and serine protease. TPP was activated by divalent cations, such as Co2+ and Mn2+, and completely inhibited by Cu 2+. Enzyme activity was optimal at pH 7.0 and 45 °C with a specific activity of 281.9 units/mg for the substrate Ala-Ala-Phe-pNA. The purified enzyme catalyzed cleavage of various synthetic tripeptides but not when proline occupied the P1 position. Purified TPP cleaved the pentapeptide Ala-Ala-Phe-Tyr-Tyr and tripeptide Ala-Ala-Phe, confirming the TPP activity of the enzyme.

Highly Productive Continuous Flow Synthesis of Di- and Tripeptides in Water

The reaction of amino acid derived N-carboxyanhydrides (NCAs) with unprotected amino acids under carefully controlled aqueous continuous flow conditions realized the formation of a range of di- and tripeptide products in 60-85% conversion at productivities of up to 535 g·L-1h-1. This required a fundamental understanding of the physicochemical aspects of the reaction resulting in the design of a custom-made continuous stirred tank reactor (CSTR) with continuous solids addition, high shear mixing, automated pH control to avoid the use of buffer, and efficient heat removal to control the reaction at 1 ± 1 °C.

Effects of a high-pressure treatment on the activity and structure of rabbit muscle proteasome

The effects were assessed of high hydrostatic pressure on the activity and structure of rabbit skeletal muscle proteasome. The pressure effects on the activity were measured by the amount of fluorometric products released from synthetic substrates under pressure and from fluorescein isothiocyanate (FITC)-labeled casein after releasing the pressure. The effects on the structure were measured by fluorescene spectroscopy under pressure, and by circular dichroism (CD) spectroscopy and surface hydrophobicity after releasing the pressure. The optimal pressure for the hydrolyzing activity of synthetic peptides was 50 MPa. The degradation of FITC-labeled casein increased linearly with increasing pressure applied up to 200 MPa, and then markedly decreased up to at 400 MPa. The changes in the tertiary structure detected by fluorometric measurement were irreversible, whereas the changes in the secondary structure were small compared with those by heat treatment. The pressure-induced activation of proteasome therefore seems to have been due to a little unfolding of the active sites of proteasome.

Enzymes in organic synthesis: Use of subtilisin and a highly stable mutant derived from multiple site-specific mutations

A subtilisin mutant (subtilisin 8350) derived from subtilisin BPN' via six-specific mutations (Met50Phe, Gly169Ala, Asn76Asp, Gln206Cys, Tyr217Lys, and Asn218Ser) was found to be 100 times more stable than the wild-type enzyme in aqueous solution at room temperature and 50 times more stable than the wild type in anhydrous dimethylformamide. Kinetic studies using ester, thio ester, and amide substrates, and the transition-state analogue inhibitor Boc-Ala-Val-Phe-CF3, indicate the both the wild-type and the mutant enzymes have very similar specificities and catalytic properties. The inhibition constant (K(i)) = 5.0 μM) for the wild-type enzyme is approximately 5 times that of the mutant enzyme (K(i)) = 1.1 μM), suggesting that the mutant enzyme binds the reaction transition state more strongly than the wild-type enzyme. This result is consistent with the observed rate constants for the corresponding ester and amide substrates; i.e. the k(cat)/k(m) values for the mutant are larger than those for hhe wild-type enzyme. Application of the mutant enzyme and the wild-type enzyme to organic synthesis has been demonstrated in the regioselective acylation of nucleosides in anhydrous dimethylformamide (with 65-100% regioselectivity at the 5'-position), in the enantioselective hydrolysis of N-protected and unprotected common and uncommon amino acid esters in water (with 85-98% enantioselectivity for the L-isomer), and in the synthesis of di- and oligopeptides via aminolysis of N-protected amino acid and peptide esters. The enzymatic peptide synthesis was carried out under high concentrations of DMF (~50%) to improve substrate solubility and to minimize enzymatic peptide cleavage. Low enantioselectivity was observed in the enzymatic transformation of non-amino acid alcohols and acids.