Proteins In Various Fractions Research Articles

Effect of storage conditions on pectic polysaccharides in common beans (Phaseolus vulgaris) in relation to the hard-to-cook defect

The importance of common beans (Phaseolus vulgaris) in addressing food insecurity cannot be underestimated. However, their utilization is hampered by development of the hard-to-cook (HTC) defect, i.e., the inability of cotyledons to soften sufficiently within a reasonable time during cooking, the presence of flatulence causing oligosaccharides, the antinutrients and the low digestibility of macronutrients. The objective of this study was to determine the effect of storage conditions (time, temperature and relative humidity) on pectic polysaccharides of selected common bean varieties during the evolution of the hard cook problem. First, alcohol insoluble residue (AIR) was extracted from the bean flour. The AIR was fractionated into water, chelator and Na2CO3-soluble pectin fractions and a hemicellulose fraction. The galacturonic acid content, neutral sugars, degree of methylesterfication (DM), degree of acetylation (DAc) and molar mass distribution for pectin fractions were determined. In addition, filterable residual protein in various fractions was estimated. Results on the acidic and neutral sugars revealed that common beans contained highly branched, arabinose-rich pectic polysaccharides. Storage of common beans for more than 4months at high relative humidity (83%) and high temperature (45°C) resulting in HTC development showed a decrease in pectin extractability in water paralleled by an increase in the alkaline-soluble fraction. Other pectin characteristics such as DM and DAc showed minor variations upon storage of beans. The hydrolysis of both starch and proteins before AIR extraction decreased with increasing storage time, temperature and relative humidity. The increase in residual starch and protein might be linked to the protein–starch hypothesis where predominance of protein denaturation leads to restricted starch gelatinization. The results reveal that the contribution of pectic polysaccharides to development of HTC defect during the storage of Canadian wonder and Red haricot common beans at elevated temperature and relative humidity is due to reduced pectin solubility. However, the influence of starch and proteins seems evident.

Two-dimensional electrophoresis of proteins in various fractions of the human split ejaculate.

Two-dimensional electrophoresis of six fractions of split ejaculates from normal men (median age 23 years, n = 6) revealed large differences in the pattern of proteins found between the prostate-enriched fractions and secretions associated with the seminal vesicles. The glandular contributions were assessed using the concentrations of spermine, zinc and prostatic acid phosphatase (PAP) for prostatic secretion, and fructose and prostaglandin E for seminal vesicle secretion in the various fractions. Aside from PAP, four additional proteins were apparently associated with the prostatic fraction, one of which shared the biochemical characteristics of the specific ventral lobe protein of the rat prostate, prostatein (molecular mass 16 000, pI 4.8). The presumptive vesicular fractions contained a large number of low molecular mass proteins (10-20 000), with widely varying pI-values. The concentration of albumin and transferrin appeared to be highest in the sperm cell enriched fractions, indicating a major contribution to the ejaculate of testicular/epididymal origin.

Separate biochemical actions of inhibitors of short- and long-term memory

In vitro effects of the antibiotics - cycloheximide, puromycin and chloramphenicol, and the sodium pump blockers - ouabain, lithium and copper, on protein synthesis in the crude mitochondrial, postmitochondrial and synaptosomal fractions of chicken forebrain were studied. In the synaptosomal fraction there was a correlation between the inhibitions produced by the sodium pump blockers, of Na +/K + ATPase activity, 14C-leucine uptake and the incorporation of 14C-leucine into protein; whereas the antibiotics only inhibited leucine incorporation into protein. The effects of these drugs on the in vivo incorporation of 14C-leucine into protein in various fractions of chicken forebrain were also studied. The results suggest that there is a biochemical link involving a sodium pump and the transport of amino acids, between nerve impulse activity and neuronal protein synthesis. This link may also interconvert short-term and long-term storage of memory.

STUDIES ON THE TURNOVER OF MOUSE BRAIN SYNAPTOSOMAL PROTEINS1

Abstract—(l) The half‐lives of the proteins of various fractions of whole mouse brain increase with increasing insolubility; the supernatant and hypotonic‐extractable proteins had half‐lives of about 13 days, whereas the membrane proteins solubilized with Triton X‐100 and SLS had half‐lives of about 18 days. The proteins of the subfractions of synaptosomes had half‐lives ranging from 15 to 19 days; those in the cytoplasm had a half‐life of 18·3 days, in the membranes, about 17 days and in the synaptic vesicles, 15·6 days.(2) Although the half‐life of the synaptic vesicles was not significantly different from that of other synaptosomal subfractions, the vesicles exhibited a different protein pattern on acrylamide gels, an observation which implies that the proteins of the vesicles are qualitatively different from those of other synaptic membranes.(3) The uptake of labelled lysine into the cytoplasm of the synaptosomes of youg mice in vivo was very rapid.(4) The data derived from the relative specific radioactivities of synaptosomal fractions compared with their whole brain analogs support the contention that a sizeable fraction of the synaptosomal cytoplasmic protein was transported to the synapse by axoplasmic flow. The relative specific radioactivities of synaptosomal membrane and synaptic vesicle proteins rose much more quickly than the comparable activities for the cytoplasmic material, and the alternate possibility of synthesis in situ is discussed.

Instrumental radioactivation analysis of selenium in biological materials

A correction procedure has been established for the instrumental radioactivation analysis of selenium in dialyzed biological materials, by means of the 19-sec isotope Se 77m. Based on the oxygen content of samples, the procedure has enabled a more accurate and sensitive determination than previous methods utilizing Se 77m for analysis of selenium in such a matrix. The amounts of selenium bound to protein in various fractions of human blood and other tissues were investigated using the technique.