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Alteration of quaternary structure and biological activity of concanavalin A (1984)

Ishii, Shin-ichi ; Abe, Yukichi ; Tanaka, Isao ; [et al.]

Springer

The protein journal 3 (1984), S. 63-71

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ISSN: 1573-4943

Keywords: concanavalin A valence ; hemagglutination ; lymphocyte activation ; subunit dissociation ; tryptophan modification

Source: Springer Online Journal Archives 1860-2000

Topics: Chemistry and Pharmacology

Notes: Abstract A major molecular species of concanavalin A (Con A), a mitogenic lectin from jack bean seeds, has a quaternary structure composed of four homologous subunits and a tetravalent sugar-binding ability. We show that the tetrameric Con A can be converted into a monovalent monomeric form by either photochemical alkylation or hydrogen peroxide/dioxane oxidation of about two tryptophan residues. A divalent dimeric derivative of Con A is also prepared by sulfomethylamidation of about four carboxyl groups. Chemical properties and mitogenic and hemagglutinating activities of these new Con A derivates are compared with those of the tetravalent Con A, as well as of the Con A derivatives that have appeared in the literature on cell biological studies. The significance of the lectin valences in lymphocyte activation and hemagglutination is also discussed.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF01024837

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Evidence for acrosin-like enzyme in sperm extract and its involvement in fertilization of the ascidian, halocynthia roretzi (1982)

Sawada, Hitoshi ; Yokosawa, Hideyoshi ; Ishii, Shin-Ichi ; [et al.]

New York, NY : Wiley-Blackwell

Gamete Research 5 (1982), S. 291-301

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ISSN: 0148-7280

Keywords: ascidian ; sperm ; acrosin-like enzyme ; protease ; lysin ; fertilization ; Life and Medical Sciences ; Cell & Developmental Biology

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Biology

Notes: The presence of a protease has been demonstrated in sperm of the solitary ascidian, Halocynthia roretzi, by using t-butyloxycarbonyl-L-Val-L-Pro-L-Arg-4-methylcoumaryl-7-amide (Boc-Val-Pro-Arg-MCA) and other arginyl or lysyl MCA derivatives as substrates. Several properties of the enzyme were investigated in a crude extract. The activity had a pH optimum near 8.0 and was enhanced by the addition of CaCl2. The Km value of 87μM was determined for Boc-Val-Pro-Arg-MCA under the optimal conditions. An apparent molecular weight was estimated to be 35,000 by gel filtration. The enzyme was inhibited with diisopropyl fluorophosphate, leupeptin, antipain, p-aminobenzamidine, Val-Pro-Arg-CH2Cl, and soybean trypsin inhibitor, but scarcely inhibited with chymostatin, elastatinal, p-chloromercuribenzoic acid, tosyl-Lys-CH2Cl, and tosyl-Phe-CH2Cl. Boc-Val-Pro-Arg-MCA, the most susceptible of the substrates examined, showed the most effective inhibition against fertilization of ascidian eggs.Thus, this enzyme in ascidian sperm extract has features closely similar to mammalian acrosin [EC 3.4.21.10], and we conclude that the enzyme is involved in fertilization as one of the lysins.

Additional Material: 2 Ill.