Susumu Hizukuri

Relationship between the distribution of the chain length of amylopectin and the crystalline structure of starch granules

Abstract The distributions of chain lengths in the amylopectins of starches from 20 species (11 A-, 6 B-, and 3 C-type) were characterised by h.p.l.c. in terms of the relationship between the molecular structure of the amylopectin and the crystalline structure of the starch granule. The weight-average chain-lengths of the amylopectins of the A-, B-, and C-type starches were in the ranges 23–29, 30–44, and 26–29, respectively. Gel-permeation chromatograms of the amylopectins debranched with isoamylase showed bimodal distributions of fractions containing long and short chains for 17 specimens (including corn, rice, potato, etc. ) and trimodal distributions, of which the fraction containing short chains had twin peaks, for wheat, tapioca, and tulip amylopectins. The correlation coefficients between the average chain-lengths of amylopectins and the fractions of long and short chains and the ratio of the fractions of short and long chains by weight were 0.90, 0.69, and −0.95, respectively. In general, amylopectin molecules of A-type starches have shorter chains in both the long- and short-chain fractions and larger amounts of the short-chain fractions than those of the B-type starches. The chain lengths of amylopectins of the C-type starches were intermediate and it is inferred that these starches possibly yield any type of crystalline structure depending on the environmental temperature and other factors, whereas the A- and B-type starches are insensitive to temperature.

Multi-branched nature of amylose and the action of debranching enzymes

Abstract Convenient and sensitive methods are described for analyses of the reducing and non-reducing residues of amylose. The multi-branched nature of amylose samples from several plant sources was revealed quantitatively by these methods. Pseudomonas isoamylase partially (30%) split the branch linkage of potato amylose. The concurrent action of Aerobacter pullulanase and sweet-potato beta-amylase hydrolysed the amylose completely.

A periodic distribution of the chain length of amylopectin as revealed by high-performance anion-exchange chromatography

Abstract The chains of amylopectin over dp 80 were separated on baseline resolution by high-performance anion-exchange chromatography with pulsed amperometric detection under improved conditions, and the chain-length (cl) distributions of amylopectins from eleven plant sources were analyzed. The differences in amount of each chain between arrowhead (Sagittaria trifolia L. var. sinensis Makino) and other kinds of amylopectins exhibited periodic waves which divided the abscissa at intervals of dp 12, except those of edible canna and yam amylopectins, where the interval was of the order of dp 15. Accordingly, chain-length distributions were fractionated into fa, dp 6–12; fb1, dp 13–24; fb2, dp 25–36, and fb3, dp >37. Amylopectin with short and long cl n had large and small amounts of the fa fraction, respectively, and showed A and B type X-ray diffractions of starch granules. The amount of the fa fraction was suggested to play an important role in the determination of starch crystalline polymorphs.

Structures of rice amylopectins with low and high affinities for iodine

Abstract The amylopectins from the apparent low- (japonica) and high-amylose (indica) varieties of rice showed, respectively, low (0.39–0.87 g/100 g) and high (1.62–2.57 g/100 g) affinities for iodine, average chain-lengths ( c.l. ) of 19–20 and 21–22, and similar beta-amylolysis limits (56–59%). Gel filtration of the isoamylase-debranched amylopectins indicated that the amylopectins showing a high affinity for iodine contained lower proportions of short chains and higher proportions (up to 14.2%) of the long chains ( c.l. , 85–180). The long chains appeared to be derived from long B-chains with side chains widely spaced and located far from the non-reducing terminus. The apparent high-amylose (30–32%) rice starches had ordinary contents (15.5–18.5%) of amylose.

Purification and structure of amylose from rice starch

Abstract A method for the purification of amylose from rice starch has been developed. The critical step was the removal of insoluble amylopectin-like contamination from crude amylose in water at 50° by ultracentrifugation at 100,000g for 1 h. The conventional autoclaving procedure was avoided. Gel-permeation chromatography and h.p.l.c. indicated the amylose specimens prepared from indica and japonica rice starches to be pure. The iodine affinities and blue values of the specimens were 20.0–21.1 g/100 g and 1.40–1.47, respectively. The amyloses had number-average d.p. ( d.p. n) values of 980–1110, average chain-lengths of 250–370, and beta-amylolysis limits of 73–84%, indicating them to be slightly branched molecules with 2–5 chains on average. The weight-average d.p. ( d.p. w) values were 2750–3320, and the high d.p. w/ d.p. n values (2.6–3.4) suggested broad distributions of molecular weights.

Measurement of the chain length of amylopectin and its relevance to the origin of crystalline polymorphism of starch granules

Abstract The average chain length a amylopectin of 27 starch samples was a aasayed by a new method and it was found that A-type starch had shorter chain lengtt than B-type starch. In addition, amylodextrin samples with shorter average chain lengths had the strong tendency to crystallize into the A-type. shorter average chain lengths had the strong tendency to crystalline into the A-type.

Estimation of the distributions of chain length of amylopectins by high-performance liquid chromatography with pulsed amperometric detection☆

Abstract High-performance anion-exchange chromatography for a detailed estimation of the distribution of chain length of amylopectins was developed using a pulsed amperometric detector under alkaline conditions. As maltosaccharides having different degrees of polymerization, which were produced by debranching of amylopectin with isoamylase, exhibit different pulsed amperometric detector responses, the individual maltosaccharides (degree of polymerization 6–17) were isolated by high-performance liquid chromatography on an amino column and an octadecylsilane column to use as quantification standards. By the use of this high-performance anion-exchange chromatography the chain length distributions of some typical amylopectins were characterized in detail.

Molecular structures of rice starch

Abstract New procedures for the structural analysis of starches are described. The beta-amylolysis limit of the branched component of seven rice amyloses was estimated to be 39% from the relationship between the beta-amylolysis limit and the number of branched molecules. The d.p. n and the proportions of the linear and branched molecules were estimated on the basis of the structures of the amyloses and their beta-limit dextrins. The limiting viscosity numbers [η] showed good correlation with the proportions of the linear and branched molecules, but not with their molecular sizes. The iodine affinity and the [η] of eight rice amylopectins were dependent on the longest chain component, which is lacking in waxy amylopectin but abundant in some indica varieties. The [η] of rice amylopectin showed a good correlation with the proportions of the components with the longest and shortest chains, but not with the molecular size.

Examination of the purity and structure of amylose by gel-permeation chromatography

Abstract Gel-permeation chromatography on TOYOPEARL HW-75F is a sensitive and useful method for examining the purity of amylose specimens. The required recrystallisation frequency for preparing amylose free from amylopectin depended on the starch source. The iodine affinities of chromatographically pure amylose specimens were 20–20.5 g/100 g. The pure kuzu, tapioca, and potato amyloses had d.p. values of 1540, 2660, and 4920, with 5, 8, and 7 chains on average, respectively. Wheat amylose obtained by aqueous leaching at 70° was a short-chain molecule ( d.p. , 570) with 2 chains on average. These amylose specimens consisted of molecules differing in molecular weight and chain length. The branched molecules showed broad distributions of molecular weight. Pseudomonas isoamylase liberated short (maltotetraose) to long (probably d.p. >100) chains from potato amylose.

Estimation of the distribution of molecular weight for amylose by the low-angle laser-light-scattering technique combined with high-performance gel chromatography

Abstract The weight-average molecular weights and distributions of molecular weight for various amyloses were estimated by high-performance gel chromatography using a low-angle laser-light-scattering photometer and a differential refractometer as detectors. The weight-average molecular weights of potato, sweet potato, tapioca, kuzu, and lily amyloses were 1,030,000 (d.p. 6,360), 880,000 (d.p. 5,430), 1,080,000 (d.p. 6,680), 518,000 (d.p. 3,220), 812,000 (d.p. 5,010), and 734,000 (d.p. 4,350), respectively. Amylose molecules are suggested to be less expanded than pullulan molecules, from the relationship between molecular weight and retention time in gel-permeation chromatography.