Glycolytic enzymes of fowl and turkey spermatozoa

• 1.1. It was confirmed that, under anaerobic conditions, fowl spermatozoa formed lactate from glucose thirteen times faster than turkey spermatozoa.
• 2.2. The profiles of glycolytic enzyme activities were similar for spermatozoa from both species; however fowl spermatozoal activities were generally 2- to 4-fold higher.
• 3.3. Exceptions were glycerophosphate mutase and lactate dehydrogenase activities which were respectively 9.5 and 41 times greater in fowl spermatozoa.
• 4.4. In both species, spermatozoal glyceraldehyde-3-phosphate dehydrogenase had the lowest activity of the glycolytic enzymes.

     

Opioid binding properties in bovine retina

Saturable binding sites for tritiated dihydromorphine ([³H]DHM), D-Ala²-D-Leu⁵-enkephalin ([³H]DADL) and etorphine were found in a crude synaptosomal preparation of bovine retina. Scatchard analysis of saturation binding curves of each ligand was curvilinear and the presence of two independent binding sites inferred. The density of binding sites of [³H]etorphine was similar to that reported in brain crude synaptosomal preparations, and the affinity for the high affinity binding site to each ligand was similar to values determined in brain. Moreover, the regulation of the binding sites by GTP and sodium was also similar to that observed in brain. Selective binding sites for [³H]DADL (δ-sites) were not detectable, although binding sites similar in nature to μ-binding sites were detected.     

NAD glucohydrolase from bovine retina

The NAD glycohydrolase activity in the retina is very low compared with the one found in the brain. Therefore the retina extracts ahve a sufficiently high NAD level so that they are able to form "in vitro" lactate from glucose in anaerobiosis in presence of only ATP, Mg++ and glucose. The NAD glycohydrolase has been found in the retina in a great extent in the microsomes.     

Glycolytic enzymes in resting spores and vegetative mycelia of Entomophthora pyriformis.

Specific activities of 14 enzymes of the Embden-Meyerhof-Parnas and pentose phosphate pathways were determined in extracts of resting spores and vegetative mycelia of Entomophthora pyriformis. All these enzymes were detected in mycelial extracts, whereas only nine were detectable in resting spore extracts. Activities of detectable spore enzymes were much lower than those of the corresponding mycelial enzymes with the exception of triosephosphate dehydrogenase, which had higher activity in spore extracts. The enzyme deficiencies noted point to the inability of either pathway to function in dormant spores.     

Glycolytic enzymes in non-photosynthetic plastids of pea (Pisum sativum L.) roots

The presence of the glycolytic enzymes from hexokinase to pyruvate kinase in plastids of seedling pea (Pisum sativum L.) roots was investigated. The recoveries, latencies and specific activities of each enzyme in different fractions was compared with those of organelle marker enzymes. Tryptic-digestion experiments were performed on each enzyme to determine whether activities were bound within membranes. The results indicate that hexokinase (EC 2.7.1.2) and phosphoglyceromutase (EC 5.4.2.1) are absent from pea root plastids. The possible function of the remaining enzymes is considered.Abbreviations GADPH glyceraldehyde 3-phosphate dehydrogenase - PFK phosphofructokinase - PFP pyrophosphate: fructose 6-phosphate 1-phosphotransferase Bronwen A. Trimming gratefully acknowledges the award of a studentship from the Science and Engineering Research Council