The preparation and properties of some gelatin fractions

Abstract

London): I was very interested in Dr. Stainsby's result that the rigidity of gelatin gels did not vary much with molecular weight, because about 30 years ago I produced a mechanical model for a gelatin gel (Trans. Furuduy Soc., 21, 114 (1925-1926)) which indicated that the rigidity should not be dependent upon molecular weight and that by inference such small variations as are observed are due to secondary effects. (London): Somebody was interested in the details of the method for determiniig rigidity and I would like to mention that they will be published in the Proceedings of the International Congress of Rheology, held this year a t Oxford. Dr. G . Stainsby

Rheology of Gels

“…It is now clear that G is independent of molecular weight above a limiting value, except either at temperatures near the gel point or at low concentrations (Ward, 1953; Ward, 1954, 1958a;Stainsby, 1954;Robinson, 1975). The weight average critical molecular weight, above which G is independent of molecular weight, is of the order of 60000 (Saunders and Ward, 1958a), though obviously it will depend to some extent upon the distribution.…”

The N-terminal amino acid residues of gelatin. 1. Intact gelatins

“…60000 g. of gelatin the range (excluding sample E) being 53 000 to 67 000. These are number-average values of the molecular weight of a molecularly heterogeneous system and the samples may well contain fractions ranging from one-quarter to 4 times this value (Pouradier & Venet, 1950;Stainsby et al 1954). The mean values are in reasonable agreement with those of Pouradier & Venet (1950), who, using similar types of gelatin, obtained values of 61000 to 67000 by osmoticpressure measurements.…”

“…1 The reduced viscosity, as defined by Stainsby, Saunders & Ward (1954) and expressed as 1/c ln 72re,L was determined at pH 7 in M-NaCl at 350, the gelatin concentration, c, being 0.5% (w/v). Under these conditions, small changes in pH or ionic strength produce only very small changes in the value of 1/c ln e The author would like to thank Dr G. Stainsby for these determinations.…”

Gelatin

“…The remaining amino acids in decreasing order are arginine [74-79-3], aspartic acid [56-84-8], lysine [56-87-1], serine [56-45-1], leucine [61-90-5], valine [72-18-4], phenylalanine [63-91-2], threonine [72-19-5], isoleucine [73-32-5], hydroxylysine [13204- , histidine [71-00-1], methionine [63-68-3], and tyrosine [60-18-4] (18)(19)(20)(21)(22)(23)(24)(25).…”