Studies on Starch Phosphate. Part 2. Isolation of Glucose 3‐Phosphate and Maltose Phosphate by Acid Hydrolysis of Potato Starch

Abstract

Three sugar phosphates, 4‐0‐(α‐D‐6‐phosphoglucosyl)‐D‐glucose, glucose 3‐phosphate, and glucose 6‐phosphate, were isolated from the α‐amylase limit phosphodextrin of potato starch by a partial acid hydrolysis and an ion exchange chromatography on Dowex‐1 × 8 formate resin. From the quantitative yields of glucose 3‐phosphate and glucose 6‐phosphate, the distribution of esterified phosphate in potato starch was estimated to be 38% on the C‐3, and 61% on the C‐6 of glucose residues. it was suggested from a kinetic study that approximately 1% of the phosphate in starch existed in a form more labile to acid than glucose 3‐phosphate, possibly as glucose 2‐phosphate.

Phosphorylation of Transitory Starch Is Increased during Degradation

“…Under in vitro conditions this reaction leads to the formation of glucan-bound Glc6P and Glc3P residues in a ratio of approximately 2:1, which is also found in native starch (Tabata and Hizukuri, 1971). The phosphorylation level of starch is quite low.…”

“…The phosphorylation level of starch is quite low. In cereal endosperm starch, the amounts of Glc6P and Glc3P residues are at or below the detection limit, and even in potato (Solanum tuberosum) tuber starch, which is regarded as highly phosphorylated, only 0.2% to 0.5% of the Glc residues are phosphorylated (Tabata and Hizukuri, 1971;Blennow et al, 2002). The phosphorylation level of leaf starch is 0.1% or less (Yu et al, 2001).…”

Characterization of Physicochemical and Functional Properties of Starch from Five Yam (Dioscorea Alata) Cultivars in Indonesia

“…The phosphorus in starch tubers are in the form of phosphate-monoester which covalently bonded to C3 or C6 of amylopectin glucose monomers in branch chain-B longer chain [39], [40]. Thus, the higher the ratio of amylose/amylopectin means the lower of amylopectin and consequently lower phosphorus content of the starch of yam than potato.…”

Starch Phosphorylation in Potato Tubers Proceeds Concurrently with de Novo Biosynthesis of Starch

“…Interna1 standards of Glc-6-P revealed more than 85% recovery during the acid hydrolysis. Thus, some of the free phosphate is derived from the hydrolysis of C-6-bound phosphate, but most of the free phosphate probably arose from hydrolysis of C-3-bound phosphate, which is more acid labile than C-6-bound phosphate (Tabata and Hizukuri, 1971). Compared with Posmo, Dianella showed slightly elevated levels of total phosphate and correspondingly elevated amounts of Glc-6-P after acid hydrolysis (Table I).…”

“…The phosphorus in potato starch is present primarily as phosphate esterified to the Glc residues of the starch. The majority of the phosphate is bound in the amylopectin fraction of the starch, whereas phosphorylation of amylose is insignificant (Hizukuri et al, 1970 of the phosphate groups are linked to C-6 of the Glc residues, the rest to C-3 (Hizukuri et al, 1970;Tabata and Hizukuri, 1971;Muhrbeck and Teiller, 1991). A small fraction (1%) may be linked to C-2 (Hizukuri et al, 1970).…”