The Tryptophan Synthetase System 1

Yanofsky, Charles

doi:10.1128/mmbr.24.2.221-245.1960

Cited by 107 publications

(55 citation statements)

References 18 publications

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“…That one protease may activate another is, of course a commonplace. That two subtmits of a macromolecule may have distinct but interrelated functional activities has been demonstrated in the tryptophane synthetase system of Esdza, ichia coli (26). In this system, however, one enzymic subcomponent does not activate another.…”

Section: Discussionmentioning

confidence: 99%

THE ENZYMATIC NATURE OF C'1r

Naff

Ratnoff

1968

The Journal of Experimental Medicine

109

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Human C'1, a macromolecular complex composed of three subunits, is the zymogen for at least two distinct enzymes. Preparations of one subunit, C'1r, functioned as a protease which converted another subunit, C'1s, to C'1 esterase. The conversion of C'1s to C'1 esterase by C'1r was blocked by Liquoid, phenyl methylsulfonyl fluoride, and calcium ions, but not by soybean trypsin inhibitor, hirudin, or heparin. Preparations of C'1r also possessed two additional functions, i.e., the ability to hydrolyze certain synthetic amino acid esters and to participate in immune hemolysis. Evidence was presented which indicates that these three functions are properties of a single entity, C'1r, but not of the same portion of its molecular structure. These observations suggest that C'1r has at least two active sites, one for its reaction with C'1q, an additional subunit of C'1, and one for its reaction with C'1s; together, the three subcomponents, C'1q, C'1r, and C'1s, form a single functional unit, the first component of complement.

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Section: Discussionmentioning

confidence: 99%

THE ENZYMATIC NATURE OF C'1r

Naff

Ratnoff

1968

The Journal of Experimental Medicine

109

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“…As a spatial unit, it has been substantiated that genes that are not structural alleles can still be functional alleles, and it was shown that the smallest unit of recombination is most probably a single nucleotide (e.g. Yanofsky 1960). Finally, in the functional unit, it was found that the gene may be part of a coordinated complex, an operon (e.g.…”

Section: Discussionmentioning

confidence: 99%

Cell Mediated Lympholysis in Man. The HL‐A Third Locus Antigen, AJ (W20) as Sensitizing and/or Target Determinant

1975

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The Indirect Cell Mediated Lympholysis (ICML) test has become a reliable in uitro tool in investigations of the immunogenetic background of the cellular immune response. I t is well established that the antigens of the LA and FOUR loci of the human Major Histocompatibility Complex (MHC) or antigens governed by closely linked loci exhibiting a marked linkage disequilibrium are of major qualitative and quantitative importance in ICML.This communication is concerned with the importance of the HL-A third series antigen AJ (W20) on lympholysis in ICML. From investigations of 47 combinations where only the AJ (W20) antigen may be attacked, it is concluded that this antigen is, in itself, a poor ICML target determinant, but that AJ (W20) may function as a stronger ICML target determinant in concert with a FOUR antigen, although the actual FOUR antigen cannot be attacked.

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“…The concept that an enzyme is made up with more than one subunit is not new. It has been studied extensively with the tryptophan synthetases of Neurospora crassa and Escherichia coli (Yanofsky, 1960). The tryptophan synthetase of E. coli is composed of at least two protein parts (Crawford and Yanofsky, 1958).…”

Section: Discussionmentioning

confidence: 99%

Complementation of Lecithinase Activities by Closely Related Pseudomonads: Its Taxonomic Implication

Bates

Liu

1963

J Bacteriol

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BATES, JANICE L. (University of Louisville School of Medicine, Louisville, Ky.) AND PING-HUI V. Liu. Complementation of lecithinase activities by closely related pseudomonads: its taxonomic implication. J. Bacteriol. 86:585-592. 1963.-A lecithinase activity was demonstrated by a mixture of cell-free extracts from two strains of closely related pseudomonads, neither of which was able to show this activity when grown alone. One component, from B-2265 (Pseudomonas aureofaciens var. nonliquefaciens), was heatlabile, nondialyzable, and antigenic. The other component, from 22/3 (P. fluorescens), was relatively heat-stable, nondialyzable, and nonantigenic. Antisera produced with the component of B-2265 alone neutralized the activity of the complete enzyme made up with both components, as well as that of similar enzymes of related species, such as P. aureofaciens, P. chlororaphis, and P. fluorescens. The taxonomic implication of these findings is discussed. The suggestion is made that determination of the serological specificity of an enzyme or its antigenic subunits is a more reliable criterion for establishing relationships of bacterial strains than methods depending on the overall similarity of biochemical activities. 585 on July 4, 2020 by guest

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The Tryptophan Synthetase System 1

Cited by 107 publications

References 18 publications

THE ENZYMATIC NATURE OF C'1r

THE ENZYMATIC NATURE OF C'1r

Cell Mediated Lympholysis in Man. The HL‐A Third Locus Antigen, AJ (W20) as Sensitizing and/or Target Determinant

Complementation of Lecithinase Activities by Closely Related Pseudomonads: Its Taxonomic Implication

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