Enzymatic activities and functional characterization of a novel recombinant snake venom proteinase from Agkistrodon Acutus

Snake venom from Agkistrodon acutus consists of a number of compounds which may potentially be used as drugs. However, it is hard to obtain enough pure protein for drug development. Recently, we reported expression and purification of a novel recombinant fibrinogenase which was named rFII. Here we reported for the first time the enzymatic activities and functional characterization of rFII. Circular dichroism spectra showed the gross conformation of FIIa and rFII to be notably similar. It is an alkaline proteinase and the amino acid sequence exhibits a high degree of sequence identity with other snake venom metalloproteinases. rFII also exhibits amidase activity against N-(p-Tosyl)-Gly-Pro-Lys-p-nitroanilide, which is specified synthetic substrate for plasmin. Functional characterization showed that rFII possesses both fibronectin and type IV collagen cleaving activities. In addition, rFII preferentially cleaved the Aalpha-chain of fibrinogen, followed by the Bbeta-chain and finally, the gamma(γ) chain was affected. Furthermore, rFII was also capable of cleaving fibrin without plasminogen activation and suppressing ADP-induced platelet aggregation. The proteolytic activity of rFII was inhibited completely by PMSF and mostly by EDTA. The cations Ca²⁺, Mg²⁺, Na⁺, K⁺ didn't affect its proteolytic activity, while Cu²⁺ and Zn²⁺ slightly inhibited this activity. Study of hydrolysis of oxidized insulin B-chain reveals that rFII preferentially cleaved oxidized insulin B-chain at the site of Val¹²-Glu¹³, Leu¹⁵-Tyr¹⁶, and Phe²⁴-Phe²⁵.     

Recombinant expression,purification, and characterization of an acyl-CoA binding protein from Aspergillus oryzae

Biotechnology Letters - To characterize biochemically the lipid metabolism-regulating acyl-CoA binding protein (ACBP) from the industrially-important fungus Aspergillus oryzae. A full-length cDNA...     

Direct anabolic metabolism of three-carbon propionate to a six-carbon metabolite occurs in vivo across tissues and species

Anabolic metabolism of carbon in mammals is mediated via the one- and two-carbon carriers S-adenosyl methionine and acetyl-coenzyme A. In contrast, anabolic metabolism of three-carbon units via propionate has not been shown to extensively occur. Mammals are primarily thought to oxidize the three-carbon short chain fatty acid propionate by shunting propionyl-CoA to succinyl-CoA for entry into the TCA cycle. Here, we found that this may not be absolute as, in mammals, one nonoxidative fate of propionyl-CoA is to condense to two three-carbon units into a six-carbon trans-2-methyl-2-pentenoyl-CoA (2M2PE-CoA). We confirmed this reaction pathway using purified protein extracts provided limited substrates and verified the product via LC-MS using a synthetic standard. In whole-body in vivo stable isotope tracing following infusion of ¹³C-labeled valine at steady state, 2M2PE-CoA was found to form via propionyl-CoA in multiple murine tissues, including heart, kidney, and to a lesser degree, in brown adipose tissue, liver, and tibialis anterior muscle. Using ex vivo isotope tracing, we found that 2M2PE-CoA also formed in human myocardial tissue incubated with propionate to a limited extent. While the complete enzymology of this pathway remains to be elucidated, these results confirm the in vivo existence of at least one anabolic three- to six-carbon reaction conserved in humans and mice that utilizes propionate.