Bound amino acids in protein-free extracts of Italian ryegrass

Abstract

3214. Use of the inhibitors fluorocitrate and parapyruvate shows that the interconversion of substrates before the formation of 8-aminolaevulic acid is consistent with an active tricarboxylic acid cycle.5. Succinate inhibits the synthesis of 8-aminolaevulic acid by suppressing the formation of succinyl-coenzyme A from citrate, i8ocitrate or ooxoglutarate after itself being first converted into fumarate, malate or oxaloacetate. The inhibition is reversed by increasing concentrations of citrate or wocitrate, but is potentiated by a-oxoglutarate.6. a-Oxoglutarate added exogenously inhibits the condensation of glycine and succinyl-coenzyme A in the formation of 8-aminolaevulic acid. 7. 5:6-Dimethylbenzimidazole also inhibits the condensation of glycine and succinyl-coenzyme A. The inhibition here is partly relieved by increasing concentrations of glycine, but not by increasing concentrations of pyridoxal 5'-phosphate.Protein-free diffusates from ryegraes were studied by Synge (1951), who showed that, whilst the greater part of the nitrogen is present as free amino acids, a substantial proportion (usually about 5 % of the nitrogen of the diffusates) could be segregated in the form of chemically bound amino acids which could be set free by acid hydrolysis. These fractions of diffusate, obtained by electrical transport in a diaphragm cell, contained also much carbohydrate; their nitrogen content was not usually much more than 01I % on dry matter. In the present paper we describe subsequent experiments aimed at characterizing more closely the forms in which bound amino acids occur in diffusates from grass. We have worked chiefly with Italian ryegrass (Lolium multiflorum Lam.), but have not found any essential differences from results previously obtained with perennial ryegrass (L. perenne L.). A few isolated experiments with diffusates from such diverse leaves as those of clover, raspberry, nettle, cabbage and potato showed that by the diaphragm-cell procedure

The non-protein nitrogen composition of grass silages: II. The changes occurring during the storage of silage

“…The 'peptide' nitrogen content of the grass, which included water soluble proteins corresponded to 32 % of the total nitrogen. Synge & Wood (1958) and Carnegie (1961) found only low concentrations of peptide-like compounds present in grasses, it is therefore, assumed that the bulk of this 'peptide' nitrogen was in fact water soluble proteins. The value of 32 % is in agreement with the figure obtained by assuming that 20% of the total nitrogen in grass is nonprotein nitrogen.…”

Haemagglutinins from Marine Sponges

“…Analytical methods. Protein was determined with the Folin phenol reagent [12], using bovine plasma albumin as standard; total carbohydrate by an orcinol method [16], expressed in terms of glucose. Silica was measured by the method of ESTES and FAUST [5] and total phosphorus as described by KING [lo].…”

Haemagglutinins from Marine Sponges

“…Protein was determined with the Folin phenol reagent [12], using bovine plasma albumin as standard; total carbo hydrate by an orcinol method [16], expressed in terms of glucose. Silica was measured by the method of Estes and Faust [5] and total phosphorus as described by King [10].…”