Hydrolysis of fourteen native dextrans by arthrobacter isomaltodextranase and correlation with dextran structure

The isomaltodextranase (EC 3.2.1.94) from Arthrobacter globiformis T6 hydrolysed thirteen dextrans to various extents (11?64% after 13 days) at initially large but gradually decreasing rates. Dextran B-1355 fraction S was, unlike the other dextrans, hydrolysed by the dextranase initially at the lowest rate among the dextrans used, but the rate was maintained for a long period with little decrease, so that the hydrolysis reached as high as 85% after 13 days. Paper chromatography of these dextran digests revealed that this dextranase produces in addition to isomaltose, one or two trisaccharides [isomaltose residues substituted by (1 →2)-, (1→3)-, or (1→4)-α-D-glucopyranosyl groups at the non-reducing D-glucopyranosyl residues] from every dextran used. It is evident that the non-(1→6)-linkages of these trisaccharide products constitute the “anomalous” linkages of the corresponding dextrans. The relative amounts of these trisaccharide products appear to indicate the approxima te relative amounts of a particular linkage among the dextrans, or the relative amounts of two kinds of linkages of each dextran. The kinds and the relative amounts of “anomalous” linkages of some dextrans were established on the basis of the trisaccharides produced by isomaltodextranase.     

Plant growth-promoting activities of alkoxycarbonylisoureas in relation to their chemical structures

A number of alkoxycarbonylisourea derivatives were synthesized and their plant growth-promoting activities examined by the rice (Oryza sativa) seedling test. Isourea compounds with an appropriate substituent such as a halogen atom or a methyl, ethyl or methoxy group at the para-position on a benzene ring in 1-alkoxycarbonyl-2-alkyl-3-phenylcarbamoylisoureas promoted the growth of rice seedlings and acted as a highly active gibberellic acid-synergist when used in combination with gibberellic acid. The common structural requirements of isourea derivatives applied well for a growth promoter and a gibberellic acid-synergist.     

Defining the "fast-reacting" thiols of myosin by reaction with 1, 5 IAEDANS.

The specificity of the fluorescent reagent N-iodoacetyl-N-(5-sulfo-1-naphthyl)ethylenediamine (1,5 IAEDANS) for a specific thiol group of myosin has been characterized by a comparison with iodoacetamide (IAA) and by observing maximal enhancement of the Ca²⁺-ATPase activity and inhibition of the K⁺-EDTA-ATPase activity of myosin. The stoichiometry of the [³H]1,5 IAEDANS bound to myosin indicates the presence of two fast-reacting thiols which correspond to the “SH₁” groups responsible for the catalytic properties of myosin. Moreover, it has been unequivocally demonstrated by gel electrophoresis that the fast-reacting thiol is located on the myosin heavy chain. A single radioactivity-labeled thiol peptide obtained from tryptic digests of myosin labeled with [³H]1,5 IAEDANS or iodo[1-¹⁴C]acetamide indicates strongly that the identical thiol was labeled by both reagents.     

Synthesis of methyl α- and β-maltotriosides and aryl β-maltotriosides

Reaction of β-maltotriose hendecaacetate with phosphorus pentachloride gave 2′,2″,3,3′,3″,4″,6,6′,6″,-nona-O-acetyl-(2)-O-trichloroacetyl-β-maltotriosyl chloride (2) which was isomerized into the corresponding α anomer (8). Selective ammonolysis of 2 and 8 afforded the 2-hydroxy derivatives 3 and 9, respectively; 3 was isomerized into the α anomer 9. Methanolysis of 2 and 3 in the presence of pyridine and silver nitrate and subsequent deacetylation gave methyl α-maltotrioside. Likewise, methanolysis and O-deacetylation of 9 gave methyl β-maltotrioside which was identical with the compound prepared by the Koenigs—Knorr reaction of 2,2′,2″,3,3′,3″,4″,6,6′,6″-deca-O-acetyl-α-maltotriosyl bromide (12) with methanol followed by O-deacetylation. Several substituted phenyl β-glycosides of maltotriose were also obtained by condensation of phenols with 12 in an alkaline medium. Alkaline degradation of the o-chlorophenyl β-glycoside decaacetate readily gave a high yield of 1,6-anhydro-β-maltotriose.     

Premature induction of amylase in pancreas and parotid gland of growing rats by dexamethasone

Studies were made on changes in the contents of α-amylase (EC 3.2.1.1) in the pancreas and parotid gland of rats during postnatal devlopment, on the premature induction of this enzyme by hormones and on the existence of specific glucocorticoid receptors in these tissues.The amylase content in the pancreas increased from the 9th day after birth and reached the adult level on the 28th day, its content in the parotid gland increased rapidly from the 16th to 28th day after birth and then rose more gradually to the adult level.Injection of dexamethasone into rats 6–8 days after birth induced increase in the amylase of the pancreas but not the parotid gland. However, injection of dexamethasone into weanling rats 21–23 days after birth resulted in precocious induction of amylase in both tissues.Specific glucocorticoid receptors were detectable in the parotid gland of rats from 6 days after birth but were almost undetectable in the pancreas until adolescence.     

Carbohydrate composition of the isolated cell walls of dermatophytes

In an attempt to evaluate taxonomic character of sugar composition of dermatophytes, the purified cell walls from 13 species are analyzed on neutral sugar composition by gas liquid chromatography. The results were principally compatible with those obtained by conventional morphological examination. Neutral sugar components of dermatophytes cell walls were mannose and glucose in the ratio of 1∶2.7 for Epidermophyton and 1∶1.4 for Microsporum. There were two types in Trichophyton, in which the ratios of mannose to glucose were 1∶1.6 and 1∶3.8. The cases of Trichophyton ferrugineum and Trichophyton mentagrophytes were exceptional. The ratio of the former was 1∶1.4, which implied the relation to Microsporum group, and the ratio of the latter was 1∶2.3, which was supposed to be the intermediate of two types of Trichophyton group. Albino type cell wall of Epidermophyton floccosum was more rich in glucose than pigmented type one.