Proteolysis in Cheddar cheese: role of coagulant and starter bacteria

1978 ◽  
Vol 45 (3) ◽  
pp. 465-477 ◽  
Author(s):  
Arthur M. O'Keeffe ◽  
Patrick F. Fox ◽  
Charles Daly
Keyword(s):  
Amino Acids ◽  
High Voltage ◽  
Free Amino Acids ◽  
Free Amino ◽  
Protein Solubility ◽  
Gel Filtration ◽  
Cheddar Cheese ◽  
Paper Electrophoresis ◽  
Small Peptides

SummaryCheddar cheese was produced free of non-starter bacteria, acidified with starter or glucono-δ-lactone and containing active coagulant (chymosin or pepsin) or inactivated coagulant (pepsin). The level and type of proteolysis in the experimental cheeses was monitored by protein solubility at pH 4·6 and in 12 % TCA, polyacrylamide gel and high voltage paper electrophoresis, gel filtration and paper chromatography. The results show that the coagulant was primarily responsible for the formation of large peptides while small peptides and free amino acids were produced principally by the starter, possibly from coagulant-produced peptides.

Contribution of rennet and starter proteases to proteolysis in Cheddar cheese

1976 ◽  
Vol 43 (1) ◽  
pp. 97-107 ◽  
Author(s):  
R. B. O'Keeffe ◽  
P. F. Fox ◽  
C. Daly
Keyword(s):  
Amino Acids ◽  
Gel Electrophoresis ◽  
Free Amino Acids ◽  
Free Amino ◽  
Gel Filtration ◽  
Cheddar Cheese ◽  
Limited Range ◽  
Peptidase Activity ◽  
Small Peptides ◽  
Micro Organisms

SummaryProteolysis in aseptic, chemically acidified (GDL) cheese and in starter cheese made under controlled bacteriological conditions (i.e. free of non-starter micro-organisms) was measured by gel electrophoresis, the formation of pH 4·6- and 12% TCA-soluble N, gel filtration and the liberation of free amino acids. The results show that rennet was mainly responsible for the level of proteolysis detected by gel electrophoresis, pH 4·6-soluble N and gel filtration i.e. large, medium and small peptides. However, rennet alone was capable of producing only a limited range of free amino acids; only methionine, histidine, glycine, serine and glutamic acid were produced at quantifiable levels (> 0·2 μmoles/g) in GDL cheese; it is suggested that free amino acids in Cheddar cheese are mainly the result of microbial peptidase activity. The levels of free amino acids in the starter cheese were considerably lower than values reported for commercial Cheddar.

scholarly journals CATABOLIC ORIGIN OF A BENCE JONES PROTEIN FRAGMENT

1968 ◽  
Vol 128 (3) ◽  
pp. 517-532 ◽  
Author(s):  
D. Cioli ◽  
C. Baglioni
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Peptide Mapping ◽  
Gel Filtration ◽  
Urinary Proteins ◽  
Small Peptides ◽  
Protein Fragment ◽  
Bence Jones Protein ◽  
Bence Jones Proteins

Gel filtration analysis of the urinary proteins of some patients with myeloma has shown the presence of "fragments" of Bence Jones proteins which correspond to the variable half of these proteins. Experiments have been carried out to establish the origin of a "fragment" observed in a patient who excreted a large amount of this protein. Labeled homologous Bence Jones protein has been injected into this and other control patients. Excretion of labeled "fragment" has been observed in all. Analysis by peptide mapping and radio-autography of this labeled "fragment" isolated from the urine showed that the invariable half of the Bence Jones protein was not excreted; it seemed thus likely that the invariable half was metabolized to small peptides and free amino acids. A labeled Bence Jones protein which was excreted without any accompanying "fragment" was injected into the patient who excreted large amounts of "fragment." No excretion of labeled "fragment" was observed. It was thus concluded that the property of being degraded to "fragment" is characteristic of some "fragile" Bence Jones proteins and is not determined by the patient. Incubation with serum or urine of the "fragile" Bence Jones protein failed to produce any "fragment." "Fragments" of Bence Jones proteins are thus most likely formed during excretion of these proteins through the kidney and are products of the catabolism of Bence Jones proteins.

EXTRACELLULAR ORGANIC NITROGEN IN USTILAGO MAYDIS FERMENTATION BROTHS

1956 ◽  
Vol 34 (1) ◽  
pp. 1195-1198
Author(s):  
Eugene L. Dulaney ◽  
E. Bilinski ◽  
W. B. McConnell
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Organic Nitrogen ◽  
Ustilago Maydis ◽  
Ammonia Nitrogen ◽  
Small Peptides ◽  
Lysine Concentration ◽  
High Level ◽  
Fermentation Broths

Free amino acids and small peptides make up most of the extracellular organic nitrogen in media from shaken and aerated Ustilago maydis fermentations. Of the 3.5 mgm./ml. ammonia nitrogen added, 2.9 mgm./ml. remained in the extracellular broth. This extracellular nitrogen contained 1.17 mgm./ml. of organic nitrogen and 1.74 mgm./ml. of residual ammonia nitrogen. At least 53% of extracellular organic nitrogen is in the form of free amino acids. Fifteen amino acids were estimated quantitatively in acid-hydrolyzed broth and a particularly high level of arginine (1.14 mgm./ml.) was found. The amounts of methionine and tryptophan in the broth were quite low but the lysine concentration 0.400 mgm./ml. was relatively high.

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