摘要:

ABSTRACTPseudomonas fluorescens GK‐5 produced up to 35 U per ml of a single extracellular pectate lyase in a gluconate‐yeast extract medium. The enzyme was purified by chromatography on CM Bio‐Gel A at pH 7.0, and on crosslinked pectate, first at pH 7.0 and then at pH 9.0. The pure enzyme (specific activity 956 U per mg protein) has a molecular weight of 42300 and an isoelectric point of 10.3. Its amino acid composition was determined. The pectate lyase is an endo enzyme, requiring calcium ions for its activity. The enzyme is maximally active at pH 9.4 and ionic strength 0.01. It has a Kmvalue of 0.10 mg polygalacturonic acid per ml and a Vmaxof 1.3 millimoles of unsaturated products released per min per mg of enzyme protein. The organism produces soft rot in potato. The enzyme macerates potato tissue optimally at about pH 8. Cell‐bound pectate lyase was also found. Molecular and kinetic properties of the cell‐bound enzyme are identical to those of the extracellul

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1978.tb00599.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTYellow lutescent tomatoes normally devoid of lycopene can be induced to produce this red pigment when treated with bioregulators such as CPTA, (2‐(4‐chlorophenylthio)‐triethylamine hydrochloride). Red light and CPTA combination stimulated the accumulation of 225 μg/g of lycopene in mature white lutescent tomatoes after a 12‐day ripening period. Tomatoes treated with CPTA but ripened in the dark produced 67 μg/g of lycopene. Far‐red light treatment of the CPTA treated tomatoes produced only 25 μg/g of lycopene. Analysis of other carotenoids showed a similar trend indicating a quantitative but not a qualitative change in carotenogenesis in lutescent tomatoes as affected by light and by bioregulators. The antagonistic effect of far‐red light toward CPTA suggested that the two effectors might work at the same reactive site i

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1978.tb00600.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTDiaminopimelate decarboxylase (EC 4.1.1.20) has been purified 173‐fold from extracts of wheat germ acetone powder. The enzyme has a pH optimum of 7.0 in phosphate buffer and a Kmfor diaminopimelate of 0.14 mM. There is an absolute requirement for activity of added pyridoxal phosphate. The Kmfor pyridoxal phosphate is 5.2 μM. Once the enzyme is exposed to pyridoxal phosphate, it is bound very tightly.The enzyme has a molecular weight of 75,000 as determined by gel filtration. L‐Lysine inhibits the reaction but only at quite high concentration. This would not appear to be the enzyme whose regulation controls the production of lysine in wheat

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1978.tb00601.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1978.tb00602.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTThe treatment of industrial enzyme preparations with ionizing radiations to reduce microbial contamination demands a thorough characterization of these enzymes in order to identify possible changes in their physico‐chemical properties. Fungal and bacterial proteases were fractionated with respect to their charge and size properties by means of thin‐layer isoelectric focusing and gel filtration, respectively.Both enzymes were highly heterogeneous on focusing: the protease from A. oryzae consists of at least fifteen multiple forms mainly in the acid pH range, the predominant component having an isoelectric point of 5. 7, whereas the protease from B. subtilis exhibited about 10 components in the alkaline pH range 7–10 with the main zone at pH 8. 2. The molecular weights of the main enzyme fractions separated by gel filtration were estimated to be 22,000 for the fungal and 16,000 for the bacterial protease.Irradiation treatment with doses up to 1 Mrad of60Co‐γ‐rays and doses much in excess (up to 20 Mrad) revealed no changes in the charge and size properties of these proteases, thereby confirming the attraction of the irradiation process for the reduction of microbial contamination of industrial enzyme pr

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1978.tb00603.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

ABSTRACTIndustrial dry fungal pectinase from A. niger was irradiated with doses (up to 1 Mrad) of60Co‐γrays effective in reducing microbial contamination. The pectinase was characterized by thin‐layer isoelectric focusing and gel filtration in order to detect possible radiation‐induced structural alterations. Thin‐layer isoelectric focusing revealed at least fifteen multiple forms with pectin‐depolymerizing activity, with isoelectric points in the range pH 4.5–7. Heterogeneity of pectinesterase was also demonstrated, the main band occurring around pH 4. By thin‐layer gel filtration the molecular weight of the pectin‐depolymerase was estimated as being about 36,000, and that of pectinesterase as about 33,000. Radiation‐induced changes of the charge properties or molecular size of the irradiated pectinase preparation were not observed. The feasibility of using ionizing radiation for the reduction of microbial contamination of industrial enzyme preparatio

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1978.tb00604.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Book Reviews in this Article:Immunological Aspects of Foods.N. Catsimpoolas, Editor.Mycotoxins and Other Fungal Related Food Problems.Joseph V. Rodricks, Editor.Methods of Protein Separation, Vol. 2. Nicholas Catsimpoolas, Editor.Food Proteins. Improvement through Chemical and Enzymatic Modification.Robert E. Feeney and John R. Whitaker, Editors.The Proteins, 3rd Ed.Hans Neurath and Robert L. Hill, Editors.Advances in Lipid Research, Vol. 15. Rodolfo Paoletti and David Kritchevsky, Editors.Free Radicals in Biology, Vol. 111. W. A. Pryor, Editor.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1978.tb00605.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY