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At least 145 records · Page 8Linked to original sources
PubMed1990

Octapeptide segments from the amino terminus of glycophorin A contain the antigenic determinants of the M and N blood groups systems.

Human red blood cells with phenotype N/N and M/M were tested in an agglutination assay with anti-N and anti-M antibodies, respectively. After incubation of the synthesized octapeptide (Leu-Ser-Thr-Thr-Glu-Val-Ala-Met) from the N-amino terminus of glycophorin A, with anti-N antibody, there was significant inhibition of the agglutination of the N-positive cells. There was also inhibition of the agglutination of the M-positive cells with anti-M antibody by the synthesized octapeptide (Ser-Ser-Thr-Thr-Gly-Val-Ala-Met) from the M-amino terminus of glycophorin A. There was no inhibition, however, of the agglutination of M-positive cells with anti-M antibodies by the N-amino terminal octapeptide. Likewise, the M-amino terminal octapeptide did not inhibit agglutination of N-positive cells with anti-N. Because the synthesized octapeptides contained no carbohydrate, the anti-N and anti-M specificity appears to be determined principally by the peptides themselves. Further studies with the use of chimeric peptides indicate that the amino terminal amino acid leucine of N-glycophorin A is a primary determinant of the N antigen, whereas the amino terminal serine of M-glycophorin A is a primary determinant for the M antigen.

Amino Acid Sequence↗
PubMed1991

Kinetically controlled synthesis of dipeptides using ficin as biocatalyst.

The application of the sulfhydryl protease ficin as biocatalyst is proposed as a novel method for enzyme-catalyzed synthesis of dipeptides. The negligible peptidase but considerable esterase activity at alkaline pH facilitated the kinetically controlled formation of peptide bonds by coupling the ester substrates Z-Ala-OMe and Z-Gly-OMe with L-alanine, D-alanine, L-glutamine, D-glutamine and L-Cys(acetamidomethyl) respectively. The reaction is accomplished without the occurrence of secondary peptide hydrolysis. Under optimum reaction conditions (pH 9.2, high ratio nucleophile/carboxyl component, 4.8% ethanol, 40 degrees C), the peptide yields ranged from 5 to 91%, depending on the structure of the amino and/or carboxyl component. No racemization was observed in the enzymatic reaction. Application of short-chain peptides has been advocated recently in clinical nutrition. Ficin-catalyzed peptide synthesis might be an attractive biotechnological approach for the synthesis of suitable dipeptides in this respect.

Amino Acids↗
PubMed1976

Lysis of tumor cells by antibody and complement. VI. Enhanced killing of enzyme-pretreated tumor cells.

The ascites form of a chemically induced guinea pig hepatoma, line-10, was resistant to killing in vitro by xenogeneic antibody and guinea pig complement. Pretreatment of line-10 cells with certain proteolytic enzymes rendered tham susceptible to the killing action of antibody and guinea pig complement. The effects of enzyme pretreatment were dependent on enzyme concentration, temperature, and could be blocked by addition of competitive or non-competitive inhibitors. The effect of the enzyme treatment could reversed by incubating the treated cells at 37 degrees C (but not at 0 degrees C), in the absence of the enzyme. Effective enzymes included ficin, bromelain, pronase, elastase, papain, trypsin, collagenase, lipases type I and type VI, and the neuraminidase preparation isolated from Clostridium perfringens. The activity of the lipase preparations and the neuraminidase preparation isolated from Clostridium perfringens appeared to be caused by proteolytic enzyme contamination. Enzyme preparations that proved ineffecitve in rendering the line-10 cells sensitive to killing by antibody and guinea pig complement included DNase, RNase, beta-glucuronidase type 6A or type B10, hyaluronidase type V or type VI, and pectinesterase.

Animals↗
PubMed1976

Complete amino acid analysis of proteins from a single hydrolysate.

An analytical procedure which affords the precise amino acid composition of a protein or a peptide from a single hydrolysate is described. This method utilizes 4 N methanesulfonic acid containing 0.2% 3-(2-aminoethyl)indole, rather then 6N HCl as a catalyst for hydrolysis. The hydrolysis is carried out in vacuo (20 mu) at 115 degrees for 22 to 72 hours. Half-cystine is determined as S-sulfocysteine by treating the hydrolysate with dithiothreitol followed by an excess of tetrathionate. The values of all amino acids, including tryptophan and half-cystine, were close to the expected theoretical values for the proteins examined. The method has the advantage that the neutralized hydrolysate can be applied directly to an ion exchange column. Further, the method is capable of distinguishing between free sulfhydryl groups as S-carbosymethylcysteine and disulfides as S-sulfocysteine. A limitation of the procedure is that tryptophan remains sensitive to the presence of carbohydrate in the sample.

Amino Acids↗
PubMed1985

The relationship between rat major acute phase protein and the kininogens.

The rat major acute phase protein (alpha 1-MAP) is a cysteine protease inhibitor. The stoichiometry of the interaction between the inhibitor and enzyme was shown to be 1:2. A cDNA clone specific for rat alpha 1-MAP was isolated from a cDNA library prepared from an inflamed rat liver RNA template. The 1458-base pair insert was sequenced and positively identified by alignment with a partial amino acid sequence obtained by radiosequence analysis of the primary translation product for alpha 1-MAP. Complete sequence analysis determined the alpha 1-MAP cDNA coded for the entire protein with the exception of the first four amino acids of the signal peptide, all of which were identified by radiosequencing. The coding sequence spans 1282 nucleotides, followed by 115 base pairs of a 3' untranslated region. Two putative active sites, suggested by the enzyme-inhibitor ratio, have been identified by analysis of internal duplications of the alpha 1-MAP sequence and the alignment of these regions with the sequences of several low molecular weight cysteine protease inhibitors. A computer homology analysis of the protein sequence revealed a 59.3% overall identity between rat alpha 1-MAP and bovine low molecular weight (LMW) kininogen. The homology included the signal peptide regions. LMW kininogen is a precursor of bradykinin. alpha 1-MAP does contain a bradykinin sequence; the flanking amino acids are different, however. Evidence for the expression of the LMW and a high molecular weight kininogen from the same gene, and the high degree of homology between these proteins and the rat acute phase protein suggest that all three proteins belong to a precisely regulated gene family.

Acute-Phase Proteins↗
PubMed1989

[Structural and functional investigation of polymyxins. Structure and biological properties of polymyxin M analogs].

The effect of proteinases of plant and microbial origin on polymyxin M was studied. It was shown that this antibiotic was absolutely stable to the effect of papain and ficin. On hydrolysis with subtilisin there formed polymyxin decyclized analogs not described earlier. Their isolation, purification and biological activity are described. The structure of these compounds was assessed by one- and two-dimensional 1H NMR spectroscopy. The role of various functional groups, their space orientation and impact on antimicrobial activity of the compounds are discussed.

Ficain↗
PubMed1989

[Synthesis of peptides, catalyzed by ficin].

Synthesis of a model peptide Z-Ala-Val-Gly-OH catalyzed by ficin in phosphate buffer was studied with water-soluble esters Z-Ala-OCH2CO-Gly-OH and Z-Ala-OCH2CO-NHC2H4SO3Na as carboxyl components. The maximal yield of the peptide was obtained at pH 8-9. The effect of temperature and concentration of reagents was studied in the model reaction.

Catalysis↗
PubMed1988

Sensitive assay of cysteine proteinases using new peptide p-nitroanilides.

N-Succinyl-glycyl-leucyl-cystein(S-benzyl) p-nitroanilide and N-succinyl-leucyl-leucyl-cystein(S-benzyl) p-nitroanilide were found to be very sensitive substrates for the assay of papain, ficin, and bromelain. These p-nitroanilides were hydrolyzed only very slightly by chymotrypsin, but not detectably by trypsin.

Bromelains↗
PubMed1975

A "new" blood factor, C1, demonstrated with extracts of seeds of the Korean Clerodendron trichotomum Thunberg.

By absorbing extracts of seeds of the Korean Clerodendron trichotomum Thunberg with selected human group O red cells, a lectin has been prepared, which defines a hitherto undescribed specificity, designated C1, defining individual differences in human red cells. The specificity C1 appears to characterize a structure associated with the A-B-H-Le marcomolecule, both of red cells and of saliva, which is distinct from the combining groups for A,B,H and Le. Moreover, the reactivity of red cells with anti-C1 lectin is destroyed by treatment of the red cells with proteolytic enzymes, unlike the reactions for A,B,H and Le.

ABO Blood-Group System↗
PubMed1980

Agglutinating phenomenon in the rat sera after administration of methylcellulose.

In the serum of Wistar rats following intraperitoneal application of methylcellulose (Kabi) the presence of the aggregation factor was confirmed. Using the more sensitive immunohaematological method-enzyme tests-we proved the agglutination phenomenon, which can be of antibody nature and cannot be induced under the test conditions in vitro by action of methylcellulose on blood cells and serum of normal rats. The described phenomenon will only occur if methylcellulose "passes" the organism of the experimental animal.

Animals↗
PubMedDate not supplied

[Affinity chromatography of a cysteine proteinase inhibitor from chicken egg protein].

A method of affinity chromatography of the inhibitor of cysteine proteinases from chick egg protein using immobilized ficin has been developed. This method yields a highly active inhibitor in an essentially homogeneous state. The molecular weight of the inhibitor is 14,000. The inhibitor suppresses the activity of ficin and papain but produces no effect on the proteolytic activity of trypsin, chymotrypsin, Asp. oryzae serine proteinase or subtilisine. Isoelectric focusing of the inhibitor has revealed the major band with pI 4.35.

Animals↗
PubMed1977

Serological studies with the ficin-antificin system.

Rabbit antisera prepared against ficin reacted with it in a series of serologic tests. Upon immunodiffusion analysis, ficin was found to consist of at least nine antigenic components. Ficin will adsorb spontaneously to erythrocytes which can be used in passive hemagglutination tests. The enzymatic activity of ficin was not abolished by antificin sera.

Animals↗
PubMed1995

Comparison of four methods to generate immunoreactive fragments of a murine monoclonal antibody OC859 against human ovarian epithelial cancer antigen.

In the present study, four different proteases (pepsin, papain, bromelain and ficin) were screened with a murine monoclonal antibody OC859, in order to verify whether different digestion procedures could improve yield and stability of the F(ab')2 or Fab fragments. The yields of F(ab')2 or Fab fragments from digestion with pepsin, papain, bromelain and ficin were respectively 20.3 +/- 2.0%, 50.5 +/- 5.0%, 74.4 +/- 2.7% and 82.8 +/- 10.2% of the theoretical maximum. Immunoreactivity in a noncompetitive solid-phase radioimmunoassay (SPRIA) of the fragments generated by the four proteases were respectively 10 +/- 5%, 36 +/- 5%, 60 +/- 6% and 75 +/- 6% of the intact OC859 IgG. These results suggested that the fragmentation of OC859 with ficin gave a higher yield of superior immunoreactive fragments.

Animals↗