ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1977.tb00165.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The ultrastructural changes occurring during germination of spores of Penicillium roqueforti were examined using transmission electron microscopy on thin sections and freeze‐etch replicas. The cell wall of the resting spore was composed of four distinct layers. The outermost layer ruptured and peeled off as the spores became swollen during the initial stages of germination. The germ tube, which emerged from the spore, had a thin cell wall which lacked the outer layers observed in the resting spore. As the germ tube transformed to mycelia it acquired extra outer layers so that the cell wall possessed three layers of material. Germinating spores were multinucleated. Membranous sacs and vesicles and endoplasmic reticulum were observed both in germinated spores and in mycelia.Freeze fracture techniques revealed that the surface of spores was covered with a layer of interwoven fibrils. This technique also confirmed the presence of distinct layers in the cell wall.The capacity of snail digestive enzymes to hydrolyze cell wall material was demonstrate

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1977.tb00166.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The cloud of pectinesterase active orange juice was stabilized by inhibiting pectinesterase competitively with pectic acid hydrolysates. Both chemically and enzymatically prepared hydrolysates with an average degree of polymerization of 8 to 15 proved to be suitable, inasmuch as their molecular weight is large enough to inhibit pectinesterase, but too small to cause juice clarification by coagulating themselves. The period of cloud stability of orange juices from various origins could be extended by a factor of 3 to 5 through the additions of 1 mg per ml of hydrolysate with a degree of polymerization of 12. The effect of delayed gelation in orange concentrates was found to be smaller, and higher concentrations of hydrolysates with a somewhat lower degree of plymerization had to be used. Measurement of methanol release proved that pectic acid hydrolysate, added to orange juice, inhibits pectinesterase.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1977.tb00167.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

A study was conducted to estimate protein quality in 4 days. Protozoan bioassays were combined with in vitro protein digestibility procedures. Data are included for 14 protein samples having a PER range of 0.68 to 2.83. In vitro protein digestibility values were in close agreement with rat apparent protein digestibility values. Two equations for predicting PER were derived from the in vitro digestibility and Tetrahymena bioassay data. Both equations have high multiple correlation coefficients (r=0.92 r=0.93). Rat PER data and computed PER data are listed. The standard deviation of the differences between the observed and computed PER is 0.28 PER (Equation 1) and 0.26 PER (Equation 2). This is compared to a standard deviation of 0.33 PER for the authors' observations of the variation in the rat bioassay.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1977.tb00168.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Phytase from California Small White beans was extracted, concentrated and enriched by heat treatment and ammonium sulfate fractionation. Crude enzyme fractions tenaciously retained endogenous phytate which could be removed by autolysis at 45°C and pH 5.2. Characterization of the phytase preparation showed: (1) increase in activity with increasing temperature from 37 to 60°C, (2) an activation energy of approximately 9,200 cal/mole for the hydrolysis of inositol hexaphosphate; (3) pH optimum of 5.2; (4) a Kmvalue of 2.22 × 10‐4M; (5) apparently partial inhibition at high substrate concentrations; (6) fully competitive inhibition by one of the reaction products, inorganic phosphate, with Ki=3.1 × 104M. These properties and kinetic constants are comparable to those reported for phytase preparations from similar sources and they adequately account for in situ autolytic loss of phytic acid from these

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1977.tb00169.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

Eight cultivars of potato tubers grown in Newfoundland were examined for total glycoalkaloids (TGA) at harvest and after 3, 6, 9 or 12 days exposure to 150 footcandles light. Freshly harvested tubers had TGA ranging from 0.9 to 15.4 mg/100 g of total tuber tissue. TGA increased as a result of long term light exposure in all cases; however, those cultivars surface‐pigmented with red or blue anthocyanins were less responsive to light induction. TGA in light exposed tubers ranged from 52–71 mg/100 g for white cultivars, 26–46 mg/100 g for red varieties, and 23–40 mg/100 g for those pigmented with blue anthocyanins. Healthy tubers from plants afflicted with potato wart did not show abnormally high TGA; however, healthy cankers contained as high as 170 mg/100 g. Greening or decomposition of wart tissue was associated with a decline in TGA. Thin‐layer chromatography revealed α‐solanine and α‐chanconine were the principal components in TGA extracts of both tubers

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1977.tb00170.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The methods of Anson (1938) and Lowry et al. (1951) were used to measure proteolysis of peanut proteins with and without papain. Spectrophotometric and colorimetric measurements of optical density for continuous assay of proteolysis in reaction mixtures yielded apparent hydrolysis curves, even in reactions that did not contain an added protease. Acceptance of these values as the sole criterion for proteolysis could lead to anomalous interpretations of results. The combined use of the above methods with disc gel electrophoresis gives a more accurate analysis of protein degradation by proteolysis.

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1977.tb00171.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

摘要:

The particulate fraction of chicken breast muscle (pH 6.5–6.7) contained 99% of the phosphofructokinase (PFK) activity. A dramatic shift from the particulate to the soluble form occurred at pH 7.05±0.10. ATP and MgATP were effective solubilizers of PFK at pH 6.7. ADP appeared to be converted to a solubilizer of PFK after incubation in the crude system. Cyclic AMP and AMP were not effective solubilizers at pH 6.7. The solubilization by ATP was dependent on the concentration of the nucleotide and could be prevented by lowering the pH to 6.0. Pyruvate, fructose‐6‐phosphate, glucose‐6‐phosphate, fructose‐1, 6‐diphosphate, glucose‐1, 6‐diphosphate, 2‐phosphoglycerate, 2, 3‐diphosphoglycerate, 3‐phosphoglycerate and pyrophosphate were not effective solubilizers at pH 6.7 at t

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1977.tb00172.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY

ISSN:0145-8884    

DOI:10.1111/j.1745-4514.1977.tb00173.x

出版商:Blackwell Publishing Ltd    

年代:1977

数据来源: WILEY