| 释义 |
protoˈpectin Biochem.
[ad. G. protopektin (A. Tschirch-Bern 1907, in Ber. d. Deut. Pharm. Ges. XVII. 242): see proto- and pectin.]
= pectose.
1908Chem. Abstr. II. 431 (heading) On pectin and protopectin. 1922Biochemical Jrnl. XVI. 704 The soluble pectin probably develops from an insoluble pectic substance contained in the cell wall... This insoluble pectin corresponds to the protopectin of Fellenberg, and to the pectose of earlier investigators. 1951Z. I. Kertesz Pectic Substances iii. 55 Protopectin is now believed by some to represent very large (and therefore water-insoluble) pectinic acid molecules. 1962S. M. Siegel Plant Cell Wall i. 16 The constitutional differences between protopectin and the other pectic substances remain unclear. Empirically, the protopectins are distinguished by their insolubility, and, in general, by a higher molecular weight. 1973J. J. Doesburg in L. P. Miller Phytochemistry I. x. 272 In most plant tissues, the pectic substances are present in the form of water-insoluble protopectin. Ripe fruits are the main exceptions having a part present in soluble form, which is formed from protopectin during the ripening process. 1976Bell & Coombe tr. Strasburger's Textbk. Bot. (rev. ed.) 64 Protopectin can..be regarded as a cementing substance holding the cells of a tissue together.
Hence protoˈpectinase [-ase] (see quots.).
1927Bot. Gaz. LXXXIII. 331 Protopectinase.—The term applied to the enzyme which hydrolyzes or dissolves protopectin, with the resultant separation of the plant cells from each other, usually spoken of as maceration. Ibid. 338 Various strains of potatoes, of a wide range of mealiness, were used as test tissue for protopectinase activity, with the idea that the most mealy might have middle lamellae most easily hydrolyzed by the enzyme. 1951Z. I. Kertesz Pectic Substances xiv. 335 Until a few years ago it was believed that protopectinase is distinct from the enzyme which hydrolyzes the 1,4 glycosidic linkages in pectinic acids... However, there is now a growing tendency toward the view that the two enzymes (protopectinase and pectin-polygalacturonase) are identical. 1973J. J. Doesburg in L. P. Miller Phytochemistry I. x. 281 In the past a specific enzyme, protopectinase, was thought to produce soluble pectic material from protopectin... Since there is no adequate proof of the existence of such a specific enzyme..it is believed that the action of ‘macerating’ enzymes is exerted by one or more of the pectic enzymes mentioned hereafter. |