Xerophytic <Emphasis Type="Italic">Cereus pterogonus</Emphasis> xylose isomerase is a thermostable enzyme

A thermostable xylose isomerase (D-xylose ketol-isomerase; EC.5.3.1.5) was isolated from the cladodes of xerophytic Cereus pterogonus. The enzyme was purified to homogeneity. SDS-PAGE analysis estimated the molecular mass of the enzyme protein at 66 kDa. The enzyme exhibited temperature optima at 60 and 80°C. Though the enzyme activity was optimum at pH 7.0, the enzyme was found to be stable in both acidic and basic pH ranges in the presence of divalent ions Mn²⁺, Co²⁺, and Mg²⁺. This enzyme may find potential use in the food and beverage industry. Published in Khimiya Prirodnykh Soedinenii, No. 2, pp. 169–170, March–April, 2008.     

Comparative characteristics of water-soluble proteins from <Emphasis Type=Italic>Larix sibirica</Emphasis>, <Emphasis Type=Italic>Picea obovata</Emphasis>, and <Emphasis Type=Italic>Abies sibirica</Emphasis> bud meristem

The amount of water-soluble proteins in bud meristem of Larix sibirica L., Picea obovata L., and Abies sibirica L. was shown to increase by 2-3 times in autumn during development of low-temperature resistance. The fractional composition of water-soluble proteins of the studied species and the amino-acid composition of groups of water-soluble proteins with different molecular weight (MW) were similar. Nitrogen accumulated as aspartic acid, glycine, and alanine in high- and medium-molecular-weight proteins. The peptides (MW < 5 kDa) typically had a high content of hydrophobic proline and hydrophilic tyrosine.     

Carbohydrates from the aerial part of <Emphasis Type=Italic>Ferula kuhistanica</Emphasis> and <Emphasis Type=Italic>F. tenuisecta</Emphasis>

Water-soluble polysaccharides, pectinic substances, and hemicelluloses were isolated from the aerial part of Ferula kuhistanica and F. tenuisecta. Their physicochemical properties were determined.     

Reaction of methylpheophorbides <Emphasis Type=Italic>d</Emphasis> and <Emphasis Type=Italic>b</Emphasis> with amines

A series of formyl analogs of chlorin e₆ 13-amides were synthesized in high yields by reaction under mild conditions of primary and secondary amines with methylpheophorides b and d. In contrast with the secondary 13-amides, tertiary 13-amides were found as two isomers differing in the orientation of the amide plane relative to the plane of the chlorin ring. Methylpheophorbides b and d were more reactive toward the amines than methylpheophorbide a.