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FORMATION OF NUCLEOSIDE DIPHOSPHATE MONOSACCHARIDES (NDP‐SUGARS) BY THE AGAROPHYTE PTEROCLADIA CAPILLACEA (RHODOPHYCEAE) 1
Author(s) -
Manley Steven L.,
Burns Deborah J.
Publication year - 1991
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.0022-3646.1991.00702.x
Subject(s) - galactose , monosaccharide , mannose , biology , sugar , biochemistry , agar , nucleoside , d glucose , chromatography , chemistry , bacteria , genetics
The following nucleoside diphosphate monosaccharides (sugar nucleotides) were identified by HPLC from Pterocladia capillacea Born and Thur.: ADP‐glucose, UDP‐glucose, UDP‐ d ‐galactose, and GDP‐glucose + mannose. GDP‐ l ‐galactose was not identified due to the lack of a standard. Several extraction methods were evaluated for their efficacy. A freeze/ thaw (liquid N 2 ) step fallowed by formic acid (1 M) extraction, reduced pressure evaporation, and solubilization in water was the preferred method. Differences in media nitrate that resulted in different tissue‐N levels (1.8, 2.3, and 3.5% dry wt) and agar yields (34, 31, and 28% dry wt, respectively) also resulted in a marked difference in UDP‐ d ‐galactose and ADP‐glucose tissue levels (decrease with increasing tissue‐N) while the levels of the other sugar nucleotide agar precursors remained unchanged. Activities of UDP‐glucose, GDP‐glucose, and GDP‐mannose pyrophosphorylases, and UDP‐D‐glucose‐4‐epimerase were detected in cell‐free extracts using unlabeled and 14 C‐labeled substrates. This study‐strongly supports the proposition that the d ‐galactose component of agar is synthesized via G‐1‐P → UDP‐glucose→ UDP‐ d ‐galactose and that, the l ‐galactoae component is produced via mannose‐1‐P → GDP‐mannose → GDP‐ l ‐galactose.