Disulfide bonds between the side chains of cysteine residues are the only common crosslinks in proteins. Bovine pancreatic ribonuclease A (RNase A) is a 124-residue enzyme that contains four interweaving disulfide bonds (Cys26-Cys84, Cys40-Cys95, Cys58-CysllO, and Cys65-Cys72) and catalyzes the cleavage of RNA. The contribution of each disulfide bond to the confonnational stability and catalyti...

The subunit assembly of bovine erythrocyte superoxide dismutase has been studied, through analysis of the effects of heat, removal of metal ion cofactors, and disulfide bond reduction, upon the dissociation of the subunits. Investigations utilizing sodium dodecyl sulfate-acrylamide gel electrophoresis and sedimentation equilibrium analysis demonstrate that the 2 polypeptide subunits of the prot...

A molecule of rabbit yG-globulin’ evidently consists of four polypeptide chains held together by interchain disulfide bonds and noncovalent interactions. Each molecule comprises a pair of similar or identical “light” chains having an approximate molecular weight of 20,000, and another pair of “heavy” chains of weight 50,000 to 55,000 (2-7). Each light chain is linked to a heavy chain and the tw...

The auxiliary α2δ subunits of voltage-gated calcium channels are extracellular membrane-associated proteins, which are post-translationally cleaved into disulfide-linked polypeptides α2 and δ. We now show, using α2δ constructs containing artificial cleavage sites, that this processing is an essential step permitting voltage-dependent activation of plasma membrane N-type (CaV2.2) calcium channel...

The Spodoptera exigua multicapsid nucleopolyhedrovirus (SeMNPV) Se8 gene was recently shown to encode the viral envelope fusion (F) protein. A 60-kDa C-terminal subunit (F1) of the 76-kDa primary translation product of this gene was found to be the major envelope protein of SeMNPV budded virus (BV) (W. F. J. IJkel, M. Westenberg, R. W. Goldbach, G. W. Blissard, J. M. Vlak, and D. Zuidema, Virol...

Bitis gabonica phospholipase A contains 118 amino acid residues in a single chain and is cross-linked by six disulfide bridges. Cyanogen bromide cleavage, and tryptic and chymotryptic digests provided the necessary overlapping peptides allowing the derivation of the complete amino acid sequence. In its primary structure the enzyme is more closely related to porcine pancreatic phospholipase A th...

Our cyanylation (CN)-based methodology for determining disulfide structure of cystinyl proteins overcomes the limitations of conventional proteolytic methods. However, the CN-based method has the potential drawback that occasionally some CN-induced cleavage fragments may not be detected. We show that CN-based methods can overcome the failure to detect fragments by demonstrating the existence of...

Homoserine dehydrogenase (HSD; 305 amino acid residues) catalyzes an NAD(P)-dependent reversible reaction between l-homoserine and aspartate 4-semialdehyde and is involved in the aspartate pathway. HSD from the hyperthermophilic archaeon Sulfolobus tokodaii was markedly activated (2.5-fold) by the addition of 0.8 mM dithiothreitol. The crystal structure of the homodimer indicated that the activ...