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D Hawke

Publications and source records attributed to D Hawke.

21 records · Page 2Linked to original sources

Mixed-function oxidase activity in a desert rodent, Notomys alexis.

1. The levels of enzymes associated with the hapatic mixed-function oxidase system, and the rates of oxidation of three substrates, are compared in the desert rodent, Notomys alexis, and the laboratory mouse, Mus musculus. 2. In general, the activity of the mixed-function oxidase system in Notomys alexis is greater than in Mus musculus. 3. Previous reports of the low rates of elimination of lipophilic compounds in the desert rodent are therefore not explicable by differences in metabolism. It is suggested that the lower rates of urine production is a more likely explanation. 4. The production of small volumes of concentrated urine is suggested to result in the longer retention of some foreign compounds.

Animals↗

Partial structure of a large canine cholecystokinin (CCK58): amino acid sequence.

A cholecystokinin molecule larger than any previously chemically characterized was purified from canine proximal small intestine mucosa. The purification procedure consisted of sequential steps of affinity chromatography, gel filtration, and high pressure liquid chromatography. Activity was detected and quantitated by radioimmunoassay with an antibody that recognized the carboxyl terminal sequence of porcine cholecystokinin. Microsequencing of the purified peptide revealed an amino terminal nonadecapeptide sequence (AQKVNSGEPRAHLGALLAR) not present in known cholecystokinin molecules followed by a nonadecapeptide sequence (YIQQARKAPSGRMSVIKNL) that corresponds exactly to the amino terminal sequence of porcine cholecystokinin 39 except for reversed positions of a Met and a Val residue. Based on the sequence analysis, immunoreactivity, and presence of biological activity in two bioassay systems, this peptide, tentatively named cholecystokinin 58, may be a biosynthetic precursor of the smaller forms previously characterized in gastrointestinal and brain tissues.

Amino Acid Sequence↗

Isolation and characterization of rat vasoactive intestinal peptide.

We have used gel filtration, ion exchange chromatography, affinity chromatography and reversed-phase HPLC to isolate vasoactive intestinal peptide from rat intestine. Microsequence analysis of 1 nmole peptide indicated that the sequence was identical to the porcine octacosapeptide VIP. In radioimmunoassay with four antisera and in the turkey pancreas bioassay, rat VIP was equipotent with highly purified preparations of porcine, human and canine VIP. A less basic rat VIP-variant was also isolated and the N-terminal decapeptide region that was sequenced was identical with that of porcine VIP.

Amino Acid Sequence↗