Carboxymethylation of Sperm Whale Metmyoglobin

Proton nuclear magnetic resonance study of histidine ionizations in myoglobins of various species. Specific assignment of individual resonances

“…The carboxymethylation conditions used here appear to preserve the native structure of the protein without consecutive processes that might lead to the exposure of normally masked histidine residues (Banaszak et al, 1963; Banaszak and Gurd, 1964;Gurd, 1970;. The titration experiments have been done under conditions in which structural alterations by acid or base have been minimized (Breslow and Gurd, 1962; Clark and Gurd, 1967; Hartzell et al, 1968a;Friend et al, 1977).…”

“…Sperm whale myoglobin was treated at pH 10.5 with a 50-fold excess of methyl acetimidate per lysine residue until the free lysine content was less than 5% (Garner and Gurd, 1975). The derivative was then treated at pH 7.0 in the dark for 24 h with a tenfold molar proportion of 4-sulfophenyl isothiocyanate (Birr et al, 1970). The Ne protecting groups were then selectively removed (Garner and Gurd, 1975;Gurd et al, 1977) by treatment for 24 h at pH 10.5 in a buffer of ammonium hydroxide-acetic acid (15:1, v/v).…”

Comparison of protein structure in the crystal and in solution. II. Tritium-hydrogen exchange of zinc-free and zinc insulin

“…6 In addition to hydrogen exchange, the reaction of azide with myoglobin as well as hemoglobin , and the enzymic activity of carboxypeptidase A (Quiocho and Richards, 1966). Not all kinetic properties are altered by crystallization, however: the reaction of myoglobin with iodoacetate (Banaszak et al, 1963), the enzymic activity of triosephosphate dehydrogenase (Murdock, 1967), and the hydrogen exchange of lysozyme (Praissman and Rupley, 1968); in such cases it may be that the motility of kinetically important regions is not affected, or that reaction involves only surface groups.…”

Contributions of individual amino acid residues to the structural stability of cetacean myoblobins

“…Chemical modification of exposed histidine residues with bromoacetate provides the most direct evidence linking the dissolved and crystalline states of myoglobin (Banazak et al, 1963;Banazak & Gurd, 1964;Hugh & Gurd, 1970a,b;Nigen & Gurd, 1973;. Patterns of reactivity in the solution and crystalline states were very similar with the exception of His-36, which proved reactive in the crystal, and in concentrated salt solutions, in keeping with the crystallographic analysis, but not under the normal salt conditions in solution (Botelho, 1975).…”