摘要:

ABSTRACTPectinesterase (EC 3.1.1.11) was extracted from peaches(Prunus persica)and partially purified by preparative free solution isoelectric focusing. On SDS‐PAGE gels, protein bands at 36.3 and 33.9 kilodaltons represented the major bands; minor bands were observed at 108.4, 40.7, and 17.0 kilodaltons. The pH optimum for pectinesterase activity in the partially purified extract was 8.0. The enzyme was stable at 30°C for 30 min between pH values of 5 and 8. Peach pectinesterase is stable when heated at 55°C for 5 min in 0.1MNaCl, 50 mMsodium phosphate, pH 7, buffer. However, residual activity decreased to 23% of 65°C for 5 min and was inactivated at 70°C for 5 min. The energy of activation of peach pectinesterase was determined to be 34, 600 J/mol °K. The Q10between 30°C and 60°C was estimated to be

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00159.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTA new process was developed to regulate the papain‐induced overtenderization of meat by using oryzacystatin, a cysteine proteinase inhibitor of rice seed origin. Meat cubes (2 × 2 × 2 cm each), aged 3 days, were treated with a 0.1 fold weight of papain solution and incubated at 8°C. The most favorable degree of tenderization resulted when a 2% papain solution was used for 2 h at 8°C. When the incubation was made for 24 h or longer, overtenderization resulted. The incubation of a meat cube with papain for the first 2 h and then with an adequate amount of added oryzacystatin for the subsequent 22 h was effective in regulating overtenderization. It was also confirmed by SDS‐polyacrylamide gel electro‐phoresis that the use of oryzacystatin under similar incubation conditions regulated the papain‐aided hydrolysis of myofibrill

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00160.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTThe major storage protein, phaseolin, of red kidney bean (Linden variety) was purified by ammonium sulfate fractionation between 3 and 4.1M.It was composed of three subunits with MW 49,000, 45,000, and 42,000 and there were no disulfide bonds.Phaseolin was treated with heat (121°C, 15 min), pH (1.0, 7.5, 9.0), urea (2 to 10M), guanidine (3 to 8.5M) and alkali (0.02NNaOH) at 35°C to destabilize the tertiary structure. Increase ofin vitroproteolysis by the prior treatments was estimated with chymotrypsin, trypsin, pepsin and pronase.Native phaseolin was more resistant than Hammarsten casein to hydrolysis by chymotrypsin, trypsin, pepsin and pronase. An equimolar mixture of chymotrypsin and trypsin gave lower proteolysis than the sum of hydrolysis by each proteinase separately. Chymotrypsin hydrolysis products of phaseolin inhibited trypsin, and trypsin hydrolysis products of phaseolin inhibited chymotrypsin.All the treatments listed above enhancedin vitroproteolysis. Phaseolin treated with 0.02MNaOH had higher hydrophobicity and higher absorbance between 240 and 350 nm than native phaseolin, indicating that its tertiary structure was destroyed.Autoclaving at pH 7.5, treatment with 8.5 Mguanidine or with 0.02 MNaOH increased the extent of proteolysis of phaseolin to a similar or higher level than Hammarsten casein. Guanidine (8.5M) destroyed the tertiary structure of phaseolin sufficiently that almost all susceptible bonds were hydrolyzed by pepsin, chymotrypsin and trypsin (and probably pronase

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00161.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTPreparative isolation of alcohol‐soluble and water‐soluble melanoidines from pale malt, caramel malt, coffee malt and malt roots was done. The distribution of melanoidines according to molecular weight and the spectral characterization of the separate fractions was studied by gel chromatography on Sephadex G‐50. The melanoidines isolated from coffee malt have the largest molecular weights and those from pale malt the smallest. The alcohol‐soluble melanoidines of malt are characterized by a greater diversity in spectra and absorbance maxima from 240 to 285 nm. The water‐soluble melanoidines absorb in the region 265

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00162.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

ABSTRACTTo investigate the effect of cellulase on increase of recovery of red bean starch precipitate, cellulases fromFusarium moniliformewere purified and applied to the production of red bean starch precipitate. Oneã‐glucosidase, two filter paper degradation enzymes (FPase), one endo‐ã‐glucanase (endo‐Cx) and one exo‐ã‐glucanase (exo‐Cx) were purified by ammonium sulfate fractionation, gel filtration and ion‐exchange chromatography.Optimum temperature and time of submersion of red beans for reduction of hardness was 50°C and 2 h. Maximum sedimentation rate of starch was obtained when the red bean was incubated in a mixture of 0.004 units/mL of FPase and 0.3 units/mL of CMCase, and maximum recovery of red bean starch precipitate was obtained with 0.004 units/mL of FPase and 0.2 units/mL of CMCase. Enzyme treatment reduced suspended solids about 40% in waste water compared with control. A little hydrolysis in cell wall, intercellular space and interstarch granular

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00163.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY

摘要:

Book reviewed in this article:Protein Absorption: Development and Present State of the Subject.David M. Matthews.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1991.tb00164.x

出版商:Blackwell Publishing Ltd    

年代:1991

数据来源: WILEY