The absorption of α‐amino acids from wort by various strains of yeasts followed a sequence which was almost independent of the conditions employed. The rate of absorption of arginine varied with the strain of yeast employed. The absorption of tryptophan and glutamic acid was affected by aeration. Proline, unabsorbed under “anaerobic” conditions was taken up during the latter part of the fermentation under aerobic conditions, and absorption was accompanied by the excretion of ninhydrin‐positive material as yet unidentified. The use of worts containing an amino acid concentration in excess of a certain maximum resulted in the production of beers containing appreciable concentrations of the less readily assimilable α‐amino acids.

No abstract

ResearchInjection of a soluble protein factor from mammalian spermatozoa triggers Ca 2+ oscillations in mammalian eggs similar to those seen at fertilization. This sperm factor also generates inositol 1,4,5-trisphosphate and causes Ca 2+ release in sea urchin egg homogenates and frog eggs. Recent studies have indicated that the sperm factor may be an inositol-specific phospholipase C (PLC) activity. This study investigated whether any of the commonly known PLC isoforms are components of the sperm factor. PLCβ, PLCγ and PLCδ isoforms were shown to be present in boar sperm extracts. However, upon column fractionation of sperm extracts, none of the PLC isoforms detected correlated with the ability to cause Ca 2+ release in eggs. In addition to our previous work on recombinant PLCs, it was also shown that PLCδ3, PLCδ4 and its splice variant PLCδ4 Alt1 fail to cause Ca 2+ release. The recently discovered 255 kDa PLCε isoform also appears unlikely to be a component of the sperm factor, as fractionation of sperm extracts on a gel filtration column demonstrated that the peak of Ca 2+ -releasing activity was associated with fractions of 30-70 kDa. These findings indicate that the sperm factor that triggers Ca 2+ release in eggs does not appear to have a known PLC isoform as one of its components.

The biosynthetic pathways involved when a-amino acids are absorbed by yeasts from a semi-defined medium simulating wort have been measured using 15N and "C isotopes. When grown in this medium under brewery conditions, a complex transaminase equilibrium system operates within the cell, showing that the theory of intact assimilation of amtno acids into yeast protein is invalid.A relatively high level of specificity was found in respect of the transfer of carbon skeletons of amino acids in the medium to carbon skeletons of yeast protein amino acids and the contributions in respect of each amino acid have been measured through out growth.Simple sugars have been shown to contribute significantly to the carbon skeletons of most amino acids found in yeast and the extent of these syntheses has been quanti tatively assessed.

No abstract