Grant H. Barlow

[17] Ancrod, the coagulating enzyme from Malayan pit viper (Agkistrodon rhodostoma) venom☆

Publisher Summary Ancrod, the coagulating enzyme from Malayan pit viper (Agkistrodon rlaodostoma) venom, is a thrombin-like enzyme that splits fibrinopeptide A from fibrinogen, in whole plasma or in purified form, producing a clot of modified fibrin. Unlike thrombin, it does not cleave fibrinopeptide B from fibrinogen and does not activate factor XIII, the zymogen of the fibrin cross-linking enzyme, and thus, in the absence of other activators, ancrod-produced clots are not cross-linked. This chapter discusses the thrombin-like (coagulant) activity of ancrod that is conveniently assayed by adding different dilutions of enzyme to a standard control blood plasma or a standard fibrinogen solution and comparing the clotting times with those obtained with different dilutions of an ancrod or thrombin standard. The chapter details the assay procedure using purified fibrinogen as substrate and explains the procedure of using control plasma. It also lists the amino acid and carbohydrate composition of ancrod.

A biological chemical and physical comparison of heparin from differential mammalian species

Abstract Since improvements in the isolation procedure have resulted in heparin of high biological activity, the question of species difference has been reexamined. We have isolated heparin from dog, beef, hog, sheep and human tissue by selective fractionation with quaternary ammonium compounds. Based on our results we would suggest that heparins isolated from various mammalian species are biologically, chemically and physically similar. The biological variations previously observed may well be a result of different degree of purity in the heparin isolated.

The reaction of p-mercuribenzoate with methemerythrin

Abstract The reaction between p- mercuribenzoate (PMB) and the sulfhydryl (SH) groups of methemerythrin has been investigated. The kinetic complexities observed have been postulated to arise from a side reaction in which the mercurial rapidly binds at one or more non-SH sites on the protein. Steady-state binding experiments confirm this rapid, extra binding.