摘要:

ABSTRACTAn extract fromJatropha curcasseeds, purified by gel filtration on Sephadex G‐75 and Sephacryl S‐200, yielded an active hemagglutinin of high purity as assessed by electrophoresis and isoelectric focussing. The hemagglutinin had a molecular weight of around 660,000 and a pI value of 5.75. The molecule was composed of two different subunits of molecular weights 23,450 and 11,500. Amino acid analysis suggested that the molecule lacked 1/2 cystine but contained a high proportion of acidic and basic amino acids. Agglutination of trypsinized erythrocytes, groups A, B and O, took place over the range pH 4–10, and was prevented byD‐galactose,D‐galactosamine andN‐acetyl‐D‐galactosamine. The hemagglutinin has only a weak binding capacity forD‐galactose. Its activity was stable up to 60°C; at 80°C activity

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1989.tb00381.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTA commercial radioassay kit for folate (Radio‐chemical Centre Amersham, England), produced for clinical analysis, has been tested for folacin assay in foodstuffs. The binding capacity of porcine binder was determined for different folates and compounds interfering with the microbiological assay. Recovery of standard addition of N5‐methyltetrahydrofolate to the foodstuffs extracts estimated by radioassay varied from 96 to 1

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1989.tb00382.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTGround beef samples were prepared from semimembranosus muscles, and beef muscle residue devoid of heme pigments was prepared by repeated washing of the ground muscle with distilled‐deionized water. When ground muscle, or muscle residue samples treated with metmyoglobin‐H2O2(4 mg metmyoglobin/g muscle residue; 1:0.1 to 1:1 for molar ratio of metmyoglobin to H2O2) were stored at 4°C for 0 or 6 days, no changes in nonheme iron content were observed. Similarly, nonheme iron content of stored samples was not affected by pH (5.5, 6.0 or 6.5). While metmyoglobin‐H2O2added to water‐extracted beef muscle residue catalyzed the oxidation of the indigenous lipids, treatment of the residue with H2O2alone had no effect on the o

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1989.tb00383.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThe two major trypsin‐chymotrypsin inhibitors ofLens culinarisMedik., LCI‐1 and LCI‐4, were purified to homogeneity from Italian red lentils by ammonium sulfate fractionation, gel and ion‐exchange chromatography. At least two more trypsin‐chymotrypsin inhibitors of minor importance were present. LCI‐1 and LCI‐4 inhibited human trypsin less (68–74%) but human chymotrypsin better (268–279%) than the respective bovine enzymes. The two inhibitors contained no carbohydrates, no methionine and no tryptophan and high contents ofcystine but no free sulfhydryl groups (seven and eight disulfide bridges for LCI‐1 and LCI‐4, respectively). In addition, LCI‐4 contained no isoleucine. The isoelectric points were 5.35 and 7.70 and the average molecular weights 10,600 and 9,900 daltons for LCI‐1 and LCI‐4, respectively. Inhibitor extracts, as well as purified inhibitors in solution, were relatively stable against heating and treatment with human gastric juice, while soaking the whole seeds overnight and subsequent boiling for two hours totally d

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1989.tb00384.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

ABSTRACTThe effect of L‐cysteine on mushroom polyphenol oxidase (PPO) activity was investigated using three spectrophotometric assays. The formation of pigment (melanin), o‐phenylquinone and cysteine‐quinone adduct from catechol were each assayed under similar conditions. Cysteine had two effects; first, a lag phase was seen when melanin formation was measured, and secondly, the rate of browning was decreased after the lag phase. The lag phase was not observed when the formation of cysteine‐quinone adduct rather than melanin formation was measured. This suggests that the lag phase observed in melanin formation is due to adduct formation and not quinone reduction. The velocity of adduct formation was similar to the velocity ofo‐phenylquinone and melanin formation without cysteine suggesting that reduction ofo‐phenylquinone to catechol was not significant. The structure of the adduct formed between cysteine ando‐phenylquinone was synthesized and unequivocally determined by NMR spectroscopy to beS‐(2,3‐dihydro

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1989.tb00385.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY

摘要:

Food, Nutrition and the Consumer. T. R. Gormley, G. Downey and D. O'BeirneQuality Control in the Food Industry. Vol. 4, 2nd Ed. Edited by S. M. Herschdoerfer

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1989.tb00386.x

出版商:Blackwell Publishing Ltd    

年代:1989

数据来源: WILEY