scholarly journals The purification and properties of a single chicken pepsinogen fraction and the pepsin derived from it

1973 ◽  
Vol 133 (1) ◽  
pp. 105-115 ◽  
Author(s):  
Margaret L. Green ◽  
Joanna M. Llewellin
Keyword(s):  
Amino Acids ◽  
Thiol Group ◽  
Enzymic Activity ◽  
Low Ph ◽  
Carboxypeptidase A ◽  
Molecular Weights ◽  
Ph Values ◽  
Purification And Properties ◽  
Terminal Amino ◽  
Low Ionic Strength

1. Evidence is given for the presence of at least five pepsinogens in a crude extract of mixed chicken stomachs. One of these was purified and could be activated to yield a single pepsin. 2. The molecular weights of the pepsinogen and pepsin were 36000 and 34000 respectively. The pepsin associated at low pH values and low ionic strength. 3. The amino acid analyses of both proteins are given. The pepsin was devoid of phosphate but contained carbohydrate. 4. The N-terminal amino acids of pepsinogen and pepsin were serine and threonine respectively. Five amino acids were released by carboxypeptidase A and it was deduced that serine may be the C-terminal one. 5. Each protein contained one thiol group per molecule as determined by titration with p-chloromercuribenzoate. The rate of the reaction was very rapid with pepsin, but much slower with pepsinogen, although the same group appeared to react in both instances. The enzymic activity of pepsin was unaffected by the modification. 6. The isoionic point of the pepsin was close to pH4.0 and the enzyme was stable for long periods at pH values up to 7.0. 7. The enzyme hydrolysed bisphenyl sulphite almost as rapidly as did pig pepsin A.

ZONE ELECTROPHORESIS OF CALF THYMUS HISTONE IN STARCH GEL

1960 ◽  
Vol 38 (4) ◽  
pp. 355-363 ◽  
Author(s):  
J. M. Neelin ◽  
E. M. Neelin
Keyword(s):  
Amino Acids ◽  
Gel Electrophoresis ◽  
Low Ph ◽  
Acid Extraction ◽  
Starch Gel Electrophoresis ◽  
Calf Thymus ◽  
Zone Electrophoresis ◽  
Starch Gel ◽  
Terminal Amino

A total of 19 zones were detected by starch gel electrophoresis of calf thymus histone in buffers of 0.02 μ below pH 5.0. Of these, 18 were evident at pH 4.9 (acetate) and 15 at pH 3.9 (formate). Above pH 5.0, aggregation interfered with resolution, but by adding 4 M urea to the gel sufficient resolution was obtained between pH 4.4 and 8.7 to distinguish a total of 22 zones. Of this total, three fast components were present only occasionally in trace amounts, and three others were resolved from the immobile aggregated histone at low pH only. At least 16 zones appeared to be native histone components. Acid extraction of the histone did not appear to cause degradation since no new N-terminal amino acids were generated by this step. Two different methods of preparation produced histone extracts with essentially the same electrophoretic properties.

scholarly journals Purification of rat intestinal maltase/glucoamylase and its anomalous dissociation either by heat or by low pH

1978 ◽  
Vol 173 (2) ◽  
pp. 553-563 ◽  
Author(s):  
P R Flanagan ◽  
G G Forstner
Keyword(s):  
New Species ◽  
Sialic Acid ◽  
Sodium Dodecyl Sulphate ◽  
Gel Electrophoresis ◽  
Polyacrylamide Gel Electrophoresis ◽  
Sodium Dodecyl ◽  
Low Ph ◽  
Precipitin Line ◽  
Molecular Weights ◽  
Ph Values

Maltase-glucoamylase, a microvillous membrane ectoenzyme, was solubilized from rat intestinal mucosa by digestion with papain and subsequently purified to homogeneity with an overall yield of 10–20%. An antibody to the purified enzyme formed a single precipitin line in immunodiffusion experiments with an intestinal homogenate. The enzyme was shown to be an acidic glycoprotein (20% sugar by weight) which contained low amounts of cysteine and no sialic acid. At pH3–6, maltase activity was slowly lost, but the enzyme was re-activated by re-adjustment of the pH to neutrality. However, in the presence of sodium dodecyl sulphate, acid pH values inactivated maltase irreversibly, and at the same time converted the enzyme (mol.wt. 500000 approx.) into five new species with apparent molecular weights ranging from 134000 to 480000 as judged by polyacrylamide-gel electrophoresis. The same five fragments were also formed by boiling the enzyme for brief periods in the presence of sodium dodecyl sulphate or urea either with or without reducing agents. The dissociated species were stable on re-electrophoresis, and amino acid analysis showed them to be very similar to each other and to the original enzyme. The bands migrated anomalously on polyacrylamide gels of different concentration, thereby preventing the assignment of precise molecular weights. It is possible that the five species may represent stable aggregates of a common monomer of the enzyme.

scholarly journals o-Quinones formed in plant extracts. Their reactions with amino acids and peptides

1969 ◽  
Vol 112 (5) ◽  
pp. 609-616 ◽  
Author(s):  
W. S. Pierpoint
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Plant Extracts ◽  
Thiol Group ◽  
Amino Group ◽  
Amino Groups ◽  
Terminal Amino Acid ◽  
Secondary Reactions ◽  
Terminal Amino ◽  
Group 5

1. The reactions of amino acids and peptides with the o-quinones produced by the enzymic oxidation of chlorogenic acid and caffeic acid have been studied manometrically and spectrophotometrically. 2. Amino acids, except lysine and cysteine, react primarily through their α-amino groups to give red or brown products. These reactions, which compete with the polymerization of the quinones, are followed by secondary reactions that may absorb oxygen and give products with other colours. 3. The ∈-amino group of lysine reacts with the o-quinones in a similar way. The thiol group of cysteine reacts with the quinones, without absorbing oxygen, giving colourless products. 4. Peptides containing cysteine react with the o-quinones through their thiol group. 5. Other peptides, such as glycyl-leucine and leucylglycine, react primarily through their α-amino group and the overall reaction resembles that of the N-terminal amino acid except that it is quicker. 6. With some peptides, the secondary reactions differ from those that occur between the o-quinones and the N-terminal amino acids. The colours produced from carnosine resemble those produced from histidine rather than those from β-alanine, and the reactions of prolylalanine with o-quinones are more complex than those of proline.

scholarly journals Hydrophobic proteins of lamellated osmiophilic bodies isolated from pig lung

1979 ◽  
Vol 183 (3) ◽  
pp. 731-736 ◽  
Author(s):  
P J R Phizackerley ◽  
M H Town ◽  
G E Newman
Keyword(s):  
Amino Acids ◽  
Organic Solvents ◽  
Total Protein ◽  
Microsomal Fraction ◽  
Lavage Fluid ◽  
Phase 2 ◽  
Terminal Amino Acid ◽  
Hydrophobic Residues ◽  
Molecular Weights ◽  
Terminal Amino

1. In addition to proteins that are insoluble in organic solvents, lamellated bodies isolated from pig lung and surfactant prepared from bronchopulmonary lavage fluid contain another group of proteins that are extracted together with lipid into the organic phase. 2. These hydrophobic proteins constitute about 40% of the total protein of lamellated bodies and about 13% of the total protein of surfactant isolated from lavage fluid, whereas less than 1% of the total protein of pig lung microsomal fraction and mitochondria is extracted by organic solvents. 3. The hydrophobic proteins of lamellated bodies were separated into four fractions and freed from phospholipid by chromatographic procedures. Their apparent molecular weights vary between 11 500 and 16 500, they contain 72–79% of hydrophobic residues and 16–22% of sulphur-containing amino-acids, and leucine is the major N-terminal amino acid in each case.

Fragmentation of Haptoglobin by Plasmin

1971 ◽  
Vol 49 (1) ◽  
pp. 90-96 ◽  
Author(s):  
F. Ofosu ◽  
D. W. Campbell ◽  
G. E. Connell
Keyword(s):  
Amino Acids ◽  
Molecular Weights ◽  
Genetic Types ◽  
Analogous Manner ◽  
Terminal Amino ◽  
Carboxyl Terminal

Human haptoglobin type Hp 1-1, is hydrolyzed by plasmin to give two dissimilar products, P1 and P2, with molecular weights of 78 000 and 17 000, respectively. The larger fragment, P1 has the same N-terminal amino acids, valine and isoleucine, as intact haptoglobin. The smaller fragment, P2, is derived from the carboxyl-terminal ends of the β-chains, and has an N-terminal serine.The haptoglobins of genetic types Hp 2-2 and Hp 2-1, which are found as a series of oligomers, are also sensitive to digestion by plasmin in an analogous manner.

Digestive Enzymes of the American Lobster (Homarus americanus)

1970 ◽  
Vol 27 (8) ◽  
pp. 1357-1370 ◽  
Author(s):  
H. Brockerhoff ◽  
R. J. Hoyle ◽  
P. C. Hwang
Keyword(s):  
Gastric Juice ◽  
Proteolytic Activity ◽  
Deae Cellulose ◽  
Homarus Americanus ◽  
Enzymic Activity ◽  
Exchange Chromatography ◽  
Ribonuclease P ◽  
Carboxypeptidase A ◽  
Molecular Weights ◽  
Nitrophenyl Phosphate

Gastric juice of lobster hydrolyzed the following substrates: triolein (enzymic activity: lipase), tributyrin ("lipase"), Azocoll(R) (proteinase), TAME and BAEE ("trypsin"), ATEE ("chymotrypsin"), HPLA ("carboxypeptidase A"), DNA (deoxyribonuclease), RNA (ribonuclease), p-nitrophenyl-phosphate (phosphatase), and p-nitrophenyl-N-acetyl-β-glucosaminide (chitobiase). (The quotation marks signify that the substrate specificities are typical of the quoted enzymes of mammalian or microbial origin. The spectra of specificities, however, of these enzymes and the corresponding enzymes of lobster are not necessarily identical.) Very low activities were found against RBB-starch (amylase) p-nitro-phenyl-α-(and β)-glucopyranoside(α- and β-glucosidase), p-nitrophenyl-β-galactopyranoside (β-galactosidase), and chitin azure (chitinase). No activities corresponding to phospholipase (lecithin), carboxypeptidase B (benzoylglycyl-L-arginine), elastase, glycylglycine dipeptidase, or leucine aminopeptidase were found.Gel filtration of gastric juice proteins on Sephadex(R) G-100 yielded estimates of molecular weights, among them: chitobiase 100,000; phosphatase 80,000; lipase 43,000; DNase 33,000; "trypsin" and ribonuclease 25,000; and two proteinases with optima around pH 4 and 8 and the low molecular weight of 12,500; proteolytic activity at pH 4 was also associated with the molecular weights 25,000 and 50,000.In ion-exchange chromatography, enzymes were eluted from DEAE-cellulose in the following sequence of increasing anionic character: chitobiase, proteinase (pH 4), proteinase (pH 8), lipase, "carboxypeptidase A," DNase, phosphatase, and "trypsin" and "chymotrypsin."Of the principal enzymes, only one (chitobiase) had its optimum at the pH 5 normal for lobster gastric juice. The lipase had an optimal pH around 7, phosphatase near 9, and "trypsin" near 8; proteolytic activity shows a maximum at pH 7–8 and another maximum, unusual for Crustacea, at pH 4.Much of the protein of gastric juice could not be connected with any enzymic activity. The proportion of nonactive protein seemed to increase with starvation of the animals. We found no evidence for the occurrence of zymogens.

THE EFFECT OF pH ON SURFACE STRUCTURE AND MORPHOLOGY OF THE EXTREME HALOPHILE, HALOBACTERIUM CUTIRUBRUM

1963 ◽  
Vol 9 (1) ◽  
pp. 53-63 ◽  
Author(s):  
D. J. Kushner ◽  
S. T. Bayley
Keyword(s):  
Surface Structure ◽  
Morphological Changes ◽  
Low Ph ◽  
Extreme Halophile ◽  
Intact Cells ◽  
Structure And Morphology ◽  
Ph Values ◽  
Pattern Characteristic ◽  
Low Ionic Strength ◽  
Sphere Formation

At low pH values much of the surface structure of Halobacterium cutirubrum is maintained, even in the absence of the high salt concentration normally needed to keep this organism from dissolving. If the pH is then raised in solutions of low ionic strength, the cells dissolve. Sphere formation takes place below pH 3 in the absence of salt, and at pH values of about 4 and about 11 in the presence of 4.5 M NaCl. In the latter, there is at first little leakage of intracellular constituents, and the surface of the spheres retains the woven pattern characteristic of the surface of the untreated cell. Below pH 3, this pattern disappears, and the cells become almost completely or completely permeable. In 1% acetic acid, NaCl and KCl have the same effect on cell morphology, in contrast to their differential effects on intact cells. The morphological changes observed appear primarily due to changes in the cell membrane, and are not caused by osmotic pressure.

ZONE ELECTROPHORESIS OF CALF THYMUS HISTONE IN STARCH GEL

1960 ◽  
Vol 38 (1) ◽  
pp. 355-363 ◽  
Author(s):  
J. M. Neelin ◽  
E. M. Neelin
Keyword(s):  
Amino Acids ◽  
Gel Electrophoresis ◽  
Low Ph ◽  
Acid Extraction ◽  
Starch Gel Electrophoresis ◽  
Calf Thymus ◽  
Zone Electrophoresis ◽  
Starch Gel ◽  
Terminal Amino

A total of 19 zones were detected by starch gel electrophoresis of calf thymus histone in buffers of 0.02 μ below pH 5.0. Of these, 18 were evident at pH 4.9 (acetate) and 15 at pH 3.9 (formate). Above pH 5.0, aggregation interfered with resolution, but by adding 4 M urea to the gel sufficient resolution was obtained between pH 4.4 and 8.7 to distinguish a total of 22 zones. Of this total, three fast components were present only occasionally in trace amounts, and three others were resolved from the immobile aggregated histone at low pH only. At least 16 zones appeared to be native histone components. Acid extraction of the histone did not appear to cause degradation since no new N-terminal amino acids were generated by this step. Two different methods of preparation produced histone extracts with essentially the same electrophoretic properties.

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