najas gracillima/tyrosine

Previously we selectively modified His (48), Arg, Lys, Asp, Glu and Trp residues in the basic phospholipase A2 from Naja nigricollis and the acidic phospholipase A2 from N. n. atra snake venoms. Evidence was obtained for the existence of separate but perhaps overlapping sites responsible,

The role of tyrosine residues in the biological activity of cytotoxin-1 was evaluated using N-bromo succinimide. N-bromo succinimide effected the oxidation of tyrosine residues in cytotoxin-1 with an increase in absorption at 260 nm. N-chloro succinimide was ineffective in the oxidation of tyrosine

This paper is an attempt to localize the critical area determining toxicity in a snake cardiotoxin. Toxin gamma is a single-chain polypeptide of 60 amino acids, which has been isolated from the venom of the African spitting cobra, Naja nigricollis. Three aromatic residues, namely, Trp-11, Tyr-22,

The complete covalent structure of a small, basic protein with cardiotoxic activity is described. This has been isolated from the venom of Naja nigricollis by gel filtration on Sephadex G-75 and gradient ion exchange chromatography on Bio-Rex 70. The cardiotoxin, molecular weight 6806 from amino

The immuno-chemical properties of Naja naja atra phospholipase A2 (NNA-PLA2) were studied by using the chemically modified PLA2 derivatives and the PLA2 homologues toward anti-NNA-PLA2 polyclonal and monoclonal antibodies. Anti-NNA-PLA2 polyclonal antibodies inhibited the enzymatic activity of

Raman spectroscopy was used to determine structural features of the native toxin alpha from Naja nigricollis, which contains only one Trp and one Tyr, and of chemically modified toxins having chromophores added to these two conserved aromatic amino acids. The percentages of secondary structure were

Reaction of phospholipase A2 (Naja naja naja) with p-bromophenacyl bromidine leads to almost complete loss of enzymatic activity. The rate of inactivation is pH-dependent with pKa equals 6.9 for the ionizing residue. p-Bromophenacyl bromide modifies 0.5 mol of histidine/mol of enzyme as judged by

An L-amino acid oxidase (LAAO), NA-LAAO, was purified from the venom of Naja atra. Its N-terminal sequence shows great similarity with LAAOs from other snake venoms. NA-LAAO dose-dependently induced aggregation of washed human platelets. However, it had no activity on platelets in platelet-rich

A proton nuclear magnetic resonance (NMR) study at 100 and 300 MHz of neurotoxin II from the venom of Middle-Asian cobra Naja naja oxiana has been performed in 2H2O and H2O solutions. By means of chemical modification and double resonance all the aromatic residue resonances have been assigned. From

Mocarhagin, a cobra venom metalloproteinase from Naja mocambique mocambique, has previously been shown to cleave selectively two mucin-like substrates on platelets and neutrophils within anionic amino acid sequences containing sulfated tyrosines. We now show that purified mocarhagin has

Methionine residues 24 and 26 of cardiotoxin VII1 from Naja melanoleuca were oxidised to sulphoxides using N-chlorosuccinimide at pH 8.5. The number of equivalents of oxidant required for complete oxidation suggested that the methionine side-chains existed in a relatively "exposed" conformational

A major phospholipase A2 (NN-XIII-PLA2) which constitutes 20% of the whole Naja naja naja venom was purified to homogeneity on CM-Sephadex C-25 column chromatography. NN-XIII-PLA2 is a basic protein with a mol. wt of 11,200 by SDS-PAGE. This enzyme has low enzymatic activity but is more toxic to

1. The L-amino acid oxidase of the monocellate cobra (Naja naja kaouthia) venom was purified to electrophoretic homogeneity. The molecular weight of the enzyme was 112,200 as determined by Sephadex G-200 gel filtration chromatography, and 57,400 as determined by SDS-polyacrylamide gel