摘要:

ABSTRACTYeast (Saccharomyces carlsbergensis) protoplasts were suspended in 0.8 M mannitol‐phosphate buffer (pH 9.2) and were labeled with dansyl chloride (GJH). When the protoplasts were washed and then ruptured in non isotonic media, and subsequently separated in a discontinuous sucrose gradient, over 92% of the radioactivity present was associated with the membrane fraction. The isolated labeled cytoplasmic membrane was solubilized in sodium dodecyl sulfate and 2‐mercaptoethanol and separated by gel filtration chromatography on Bio gel P‐100 and P‐150 columns. The elution pattern showed three peaks of radioactivity, but the bulk of protein, which eluted in the void volume, was found to have a comparatively low level of radioactivity. This suggests that there was selectivity in the labeling reaction, i.e. only certain proteins are exposed in such a way as to be accessible to labeling by dansylation. We suggest these proteins are at the protoplast surface. It is suggested that there are three or possibly four polypeptides which have an N‐terminal group exposed on the outer surface of the yeast

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1980.tb00637.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

ABSTRACTA membrane‐associated CDP‐1,2‐diacyl‐sn‐glycerol (CDP‐diacylglycerol):myo‐insitol phosphatidyltransferase activity (phosphatidylinositol synthase, EC 2.7.8), was identified and partially characterized from a microsome preparation of germinating soybean seeds. The pH optimum for enzyme activity was pH 8.2 with Tris‐HCl buffer. The dialyzed enzyme preparation had an absolute requirement for manganese (5 mM) or magnesium ions (50 mM). Increasing levels of Triton X‐100 at molar ratios of 1:1 to 12:1 of Triton X‐100 to CDP‐diacylglycerol stimulated phosphatidylinositol synthase activity (about 10‐fold) to a maximum followed by an inhibition of activity as the molar ratio was raised beyond the point of maximum activity. Phosphatidylserine, phosphatidylethanolamine, phosphatidylglycerol,sn‐glycero‐3‐P,and choline inhibited activity while nucleotides stimulated activity. Phosphatidylinositol synthase activity was found to be thermally inactivat

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1980.tb00638.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

ABSTRACTThe activity of mitochondria and the pectic enzymes, pectinesterase (PE) and polygalacturonase (PG), isolated from tomato fruit was inhibited by the addition of high concentrations of calcium ions. These effects could explain the complete inhibition of ripening of whole tomato fruit obtained when infiltrated with substantial amounts of calcium. The addition of lower concentrations of calcium were found to stimulate mitochondrial and PE activity, but PG activity at pH 4.5 was inhibited by concentrations greater than 10−7

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1980.tb00639.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

ABSTRACTSafflower oil, methyl oleate, and methyl linoleate were oxidized in a closed system where they were in contact with vapor space over previously oxidized methyl linoleate. The volatile compounds resulting from linoleate oxidation greatly accelerated peroxidation of the oil and the two esters. Similar results were obtained when safflower oil and methyl esters of oleic acid and linoleic acid were contacted with vapor phase over hexanal or 2,3‐decadienal, both of which are major products of decomposition of peroxides formed from peroxidized linoleat

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1980.tb00640.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

ABSTRACTA microsomal fraction which catalyzes the oxidation of the membrane lipid in the presence of NADH and Fe has been isolated from the muscle of red hake. Unlike other microsomal membrane systems previously reported which prefer, and in some cases require, NADPH, very little lipid oxidation is observed with NADPH in the fish muscle system. The enzymic nature of the reaction is indicated by the preference of NADH versus NADPH, the inhibitory effect of high concentrations of NADH, and the loss of the activity of the system upon heating. The effect of temperature on production of TBA‐reactive substances and the loss of NADH from the reaction medium was followed. There is a sharp decline in production of TBA‐reactive substances between 6°C and 0°C. Phosphate buffer was shown to inhibit the oxidation compared to histidine buffer at low concentrations of ADP. High concentrations of ADP were inhibitory to the lipid peroxidation system when histidine was used as b

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1980.tb00641.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

ABSTRACTControlled gas environments were maintained by a novel aeration system in solid substrate fermentations for enhanced protein recovery from pressed alfalfa residues. High oxygen pressures stimulated biomass and enzyme production by an Aspergillus species, isolated from alfalfa, which produced cellulase and pectinase activities in growth‐associated metabolism. High carbon dioxide pressures also stimulated enzyme production, but had less effect on biomass production, as estimated from the dissimilation of plant solids. Cellulase and pectinase activities were generally related to protein recoveries. Recoveries were up to 50% higher than those obtained by mechanical extraction, with maximum recoveries of nearly 70% of crude protein contents. Proteins not recovered at high cellulase and pectinase activities were believed to be in structurally bound forms not amenable to recovery by non‐proteolytic enzymes. Buffering at pH8 and autoclaving of residues prior to fermentation had little effect on protein recoveries. Controlled gas environments are seen to offer an interesting potential for optimizing industrial fermentation processes for the production of microbial enzy

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1980.tb00642.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

ABSTRACTRelatively intact chloroplasts were isolated from alfalfa leaf. It was determined that the chloroplasts accounted for an average of 39.2% of the total nitrogen in the leaf tissue. When extracted with Tris‐sucrose buffer, approximately 55% of the chloroplastic nitrogen was insoluble, some 28% was soluble, and approximately 16% was nonprotein nitrogen. Thus approximately 11% of the total crude nitrogen of alfalfa leaf comes from soluble protein of the chloroplasts. During the normal process of tissue disruption to extract leaf proteins this chloroplastic soluble protein, or a good part of it, would be included in the pool of leaf soluble proteins.The distribution of nitrogen between the insoluble and soluble protein fractions and the NPN fractions was determined by extraction into a Tris‐sucrose buffer solution after sonication. Triton X‐100, sodium desoxy‐cholate, sodium trichloracetate, sodium perchlorate, trypsin, and phospholipase A were tested for their efficacy in converting insoluble to soluble nitrogen. All of these agents except phospholipase gave some improvement in the extraction of nitrogen from the chloroplasts. The, greatest increase was given by the chaotropic agent, sodium perchlorate. The perchlorate, however, interfered with the micro‐Kjeldahl procedure for nitrogen determination. Therefore, the solution had to be dialyzed before protein could be determined. Considerable amounts of NPN were obtained after dialysis which could have been produced by the action of proteolytic enzymes during the extended period required for the dialysis procedure. Trypsin increased the extraction but produced excessive amoun

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1980.tb00643.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

Book reviewed in this article:Postharvest Biology and Biotechnology. Edited by Herbert O. Hultin and Max Milner.Water Activity and Food. Edited by John A. Troller and J. H. B. Christian.Lipids as a Source of Flavor. Edited by M. K. Supran.Electrical Interactions in Molecular Biophysics. Edited by Raymond Gabler.Functionality and Protein Structure. Edited by A. Pour‐El.Enzyme Engineering, Vol. 3. Edited by E. Kendall Pye and Howard H. WeetallMethods in Enzymology Vol. 46, Affinity Labeling. Sidney P. Colowick and Nathan 0. Kaplan Editors‐in‐Chief. Edited by William B. Jakoby and Meir WilchekHigh Performance Thin‐layer Chromatography. Edited by A. Zlatkis and R. E.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1980.tb00644.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY