Digestive processes of haematophagous insects. XIII. Evidence for the digestive function of midgut proteinases of Glossina morsitans morsitans Westwood (Diptera: Glossinidae)

1977 ◽  
Vol 55 (9) ◽  
pp. 1557-1562 ◽  
Author(s):  
R. H. Gooding
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Proteolytic Enzymes ◽  
Gel Filtration ◽  
Glossina Morsitans Morsitans ◽  
Glossina Morsitans ◽  
Anterior Section ◽  
Digestive Function ◽  
Posterior Section

Trypsin (EC 3.4.21.4), proteinase VI, proteinase VII, aminopeptidase (EC 3.4.11.1), carboxypeptidase A (EC 3.4.12.2), and carboxypeptidase B (EC 3.4.11.3) occur in the posterior section of the midgut of unfed male and female Glossina morsitans morsitans Westwood, and their activities rise after a blood meal. Only traces of these enzymes occur in the anterior section of the midgut. Elution profiles of proteins during Sephadex gel filtration of the anterior midgut at various times after feeding, and the low ratio of free amino acids to protein in the lumen of the anterior section of the midgut indicate that no significant hydrolysis of protein takes place there. Results of Sephadex® gel filtration of material from the posterior section of the midgut indicate that proteins are rapidly converted to peptides and free amino acids, which occur in high concentration there. The results are interpreted as indicating that digestion of proteins takes place only in the posterior section of the midgut, and that all six proteolytic enzymes have a digestive function.

A study on the degradation of arachin by proteolytic enzymes

1973 ◽  
Vol 51 (11) ◽  
pp. 2217-2222 ◽  
Author(s):  
R. B. van Huystee
Keyword(s):  
Amino Acids ◽  
Proteolytic Activity ◽  
Free Amino Acids ◽  
Free Amino ◽  
Proteolytic Enzymes ◽  
Disc Electrophoresis ◽  
Polyacrylamide Gels ◽  
Macromolecular Protein

The prime purpose of this proteolysis study was to direct attention to alternate means of measuring proteolytic activity other than the determination of free amino acids. The release of peptides from a macromolecular protein during incubation with either papain, pronase, or trypsin was determined by measuring the presence of 280-nm-absorbing molecules in the fractionation range of Sephadex G 25 eluant after incubation. The formation of larger proteinaceous constituents by proteolysis of arachin was analyzed by disc electrophoresis on polyacrylamide gels. Using these techniques it was noted that papain was the most efficient proteolytic agent for the degradation of arachin.

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.

Analytische Untersuchungen des Wehrsekretes von Peripatopsis moseleyi (Onychophora) / Analytical Investigations of the Defensive Secretion from Peripatopsis moseleyi (Onychophora)

1977 ◽  
Vol 32 (1-2) ◽  
pp. 57-b ◽  
Author(s):  
Harald Röper
Keyword(s):  
Amino Acids ◽  
Glutamic Acid ◽  
Aspartic Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Defensive Secretion ◽  
Gel Filtration ◽  
Total Content ◽  
Gas Liquid Chromatography ◽  
Isoleucine Leucine

The defensive secretion of Peripatopsis moseleyi (Onychophora) consists of 84% water and 16% protein and free amino acids. The secretion’s defensive effectiveness is an anti-predator “sticking” action. The secretion is flung out of the oral papillae in liquid state. It is then denaturized by the air and develops increasingly sticky white threads, probably through the devel­opment of disulfide bridges from the protein content. The elastic properties of the secretion threads indicate a micellar structure. The defensive secretion contains no volatile organic components or carbohydrates. This was confirmed by gas- liquid chromatography and thin-layer chromatography. After acidic hydrolysis of the secretion the following amino acids were determined quantita­tively: aspartic acid, threonine, serine, proline, glutamic acid, glycine, alanine, valine, cysteine, methionine, isoleucine, leucine, tyrosine, phenylalanine, lysine, histidine and arginine. A “rare” amino acid was not identified. Tryptophane was not present (basic secretion hydrolysis). The quantita­tive determination of free amino acids, based on the total content, showed the following results: glycine (40.9%), glutamic acid (10.8%), aspartic acid (2.65%), lysine (1.3%). This result shows, that the secretion is stored in a watery glycine/glutaminic acid buffer in the oral papillae of Peripatopsis moseleyi. High voltage paper electrophoreses and gel filtration experiments with dextran and agarose gels showed, that the secretion protein consists of, at least, two fractions with different molecular weight.

The venom of the honeybee (Apis mellifera): free amino acids and peptides

1968 ◽  
Vol 46 (10) ◽  
pp. 1221-1226 ◽  
Author(s):  
David A. Nelson ◽  
Rod O'Connor
Keyword(s):  
Amino Acids ◽  
Apis Mellifera ◽  
Amino Acid ◽  
Solvent Extraction ◽  
Free Amino Acid ◽  
Free Amino Acids ◽  
Free Amino ◽  
Gel Filtration ◽  
Automated Analysis ◽  
Electrical Excitation

The venom of the honeybee (Apis mellifera), obtained by electrical excitation, was fractionated by solvent extraction and gel filtration. The free amino acid and peptide content was determined by automated analysis. Less than 1% of the venom consisted of 19 free amino acids, while the minimum quantity of the 14 peptides was 15%. Two histapeptides were isolated and characterized. The sequence of histapeptide A was alanyl-glycyl-prolyl-alanyl-glutaminyl-histamine.

Organic Analysis of Hevea Latex. IV. Amino Acids

1941 ◽  
Vol 14 (3) ◽  
pp. 659-663 ◽  
Author(s):  
R. F. A. Altman
Keyword(s):  
Amino Acids ◽  
Free Amino Acids ◽  
Free Amino ◽  
Preliminary Analysis ◽  
Proteolytic Enzymes ◽  
Hydrolytic Degradation ◽  
Acetone Extract ◽  
Nitrogen Compounds ◽  
Organic Analysis ◽  
Hydrolysis Of

Abstract The presence of amino acids in fresh latex was reported by Belgrave in 1925. On the basis of certain considerations, he considered it improbable that his experiments involved any profound changes in the original state of the nitrogen compounds. Accordingly the amino acids which he isolated must have been present in the free state in latex. It may be noted here that Belgrave's experiments did not completely exclude either chemical or enzymatic hydrolysis of proteins. Indeed, his amino acids were separated from a serum which was prepared by acidifying fresh latex with acetic acid (20 cc. of 10 per cent acid per liter of latex) and heating gently, with no precautions whatever for inactivating any proteolytic enzymes which may have been present. Aside from Belgrave's paper, there have been only two published references to the presence of amino acids in rubber or latex. Whereas Whitby, Dolid, and Yorston reported the isolation of valine from the acetone extract of crepe rubber, McGavack and Rumbold were able to isolate d-alanine from the serum of old ammoniated latex. There is no reason whatever for assuming from these observations that valine and alanine also occur free in latex. Indeed it would be impossible to give any guaranty that there was no hydrolytic degradation of proteins in the sample. In view of this situation it seemed highly desirable, as part of a systematic organic analysis of latex, to investigate more exactly the free amino acids which are present in latex. In addition to Belgrave's observation a preliminary analysis of fresh bottom latex which had been prepared for other purposes indicated that free amino acids actually do occur in latex. The object of the present paper is to identify the amino acids occurring in latex and, so far as is feasible, to determine the quantity also.

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.

Digestive processes of haematophagous insects. XI. Partial purification and some properties of six proteolytic enzymes from the tsetse fly Glossina morsitans morsitans Westwood (Diptera: Glossinidae)

1976 ◽  
Vol 54 (11) ◽  
pp. 1950-1959 ◽  
Author(s):  
R. H. Gooding ◽  
B. M. Rolseth
Keyword(s):  
Proteolytic Enzymes ◽  
Substrate Inhibition ◽  
Gel Filtration ◽  
Deae Cellulose ◽  
Glossina Morsitans Morsitans ◽  
Tsetse Fly ◽  
Partial Purification ◽  
Glossina Morsitans ◽  
Molecular Weights ◽  
Diethylaminoethyl Cellulose

By O-(diethylaminoethyl)cellulose (DEAE-cellulose) chromatography, affinity chromatography, and Sephadex gel filtration, six proteolytic enzymes active in alkaline medium have been found in the digestive portion of the midgut (tissue and lumen contents) of adult Glossina morsitans morsitans. By use of synthetic substrates the enzymes have been characterized as aminopeptidase (AP; EC. 3.4.11.1), carboxypeptidase A (CPA; EC 3.4.12.2), carboxypeptidase B (CPB; EC 3.4.12.3), trypsin (EC 3.4.21.4), a trypsinlike enzyme designated proteinase VI, and a chymotrypsinlike enzyme designated proteinase VII. By Sephadex G-100 gel filtration the molecular weights were estimated to be 20 000 for trypsin, 19 000 for proteinase VI, 35 500 for proteinase VII, 30 000 for CPA, 22 000 for CPB, and [Formula: see text] for AP. The Km values (mg/ml) for haemoglobin were 3.43 for trypsin, 2.45 for proteinase VI, 3.68 for proteinase VII, and 2.42 for CPA. The Km values for casein were 1.22 for trypsin and 1.38 for proteinase VII. Casein showed substrate inhibition when hydrolyzed by proteinase VI and VII. Neither haemoglobin nor casein was hydrolyzed by AP and CPB. The pH optima were determined for hydrolysis of casein and the synthetic substrates.

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