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S W Ryder

Publications and source records attributed to S W Ryder.

7 recordsLinked to original sources
PubMed1981

Extraction and immunochemical characterization of cholecystokinin-like peptides from pig and rat brain.

Two major classes of immunoreactive cholecystokinin peptides (iCCK) have been identified in rat and pig brains: (i) large basic peptides (big iCCK) resembling the 33-amino acid porcine cholecystokinin (pCCK33) in size and charge; (ii) small acidic peptides (small iCCK) resembling the COOH-terminal fragments of CCK. Boiling 0.1 M HCl maximally extracts big iCCK; boiling 0.1 M NaOH maximally extracts small iCCK. The differences in hormonal forms removed by these extractants are not likely to be due to enzymatic conversion during the extraction procedures. Fractionation on Sephadex G-50 and starch gel electrophoresis combined with radioimmunoassay using three antisera of different specificities--(i) directed towards the NH2 terminus of pCCK33, (ii) produced by immunization with COOH-terminal fragment CCK8, (iii) produced by immunization with COOH-terminal fragment CCK4--are consistent with the hypothesis that a major fraction of big iCCK may represent intact cholecystokinin with a COOH-terminal extension, as has recently been suggested for gastrin, a molecule having a COOH-terminal pentapeptide identical with that of cholecystokinin.

Animals↗
PubMed1981

Radioimmunoassay of leucine-enkephalin-like substance in human and canine plasma.

Fasting human plasma immunoreactive leu-enkephalin (ir-leu-enkephalin) measured by radioimmunoassay averages 54+/-10 pg/ml. The method depends on acidification of plasma to protect against destruction of the peptide, adsorption to XAD-2 resin, extraction from the resin by aqueous methanol and concentration by evaporation. Plasma enkephalin in the dog increased from 13 to 56 pg/ml following insulin-induced hypoglycemia.

Adult↗
PubMed1980

Further characterization of brain cholecystokinin-converting enzymes.

The brain cholecystokinin-converting enzymes that cleave intact cholecystokinin to its COOH-terminal dodecapeptide and octapeptide also cleave the synthetic dipeptides Arg-Ile (or Arg-Val or Arg-Leu) and Arg-Asp, respectively. Thus, they are not hormone-specific enzymes but are bond-specific. Ultracentrifuge studies demonstrate that there is Arg-Ile hydrolase activity associated with a protein greater in molecular weight than gamma globulin and that both Arg-Ile and Arg-Asp hydrolase activities are associated with one or more proteins between albumin and gamma globulin in molecular weight.

Animals↗