Starch granules were prepared from mature grains of 9 samples of Amayanthus and 4 samples of Chenopodium quinoa. By the ordinary gel permeation chromatograph (GPC) of Pseudomonas isoamylase-debranched starch materials, the amylose content of amaranth starches was in a range of 0-28%. Thus, we confirmed that there were normal, low amylose, and waxy types of amaranth starches. The amylose content of quinoa starches was 25-27%. The ratio of short chains to long chains of amylopectin of these starches was in a range of 2.2-3.3 and somewhat lower than or similar to that of normal maize starch. Isoamylase-debranched materials were separated by HPLC with a differential refractometer (RI) and low-angle laser light-scattering photometer (LALLS) as detectors as one means, and by high-performance anion exchange chromatography with a pulsed amperometric detector (HPAEC-PAD) as the other. We found that amylopectins of Amayanthus and Chenopodium quinoa had increased amounts of long B chains and decreased amounts of short chains as compared to the waxy maize amylopectin, however, they had increased amounts of short chains with DP (degree of polymerization) from 8 to 12. Amaranth starches had slightly higher temperatures of gelatinization (T0, Tp and Tc) and smaller heats of gelatinization (d H) by differential scanning calorimetry (DSC) as compared to normal maize starch. Quinoa starches showed lower T0, T p and T and smaller ΔH. Amaranth and quinoa starch granules were digested by amylases faster than those of normal maize.
α-L-Fucosidase partially purified from porcine liver was used for the regioselective synthesis of α-L-fucopyranosyl di- and trisaccharides with p-nitrophenyl a-L-fucopyranoside (Fuc α-pNP) as the donor. In a transglycosylation reaction with p-nitrophenyl β-D-galactopyranoside (Gal β-pNP) as the accep-tor, the enzyme formed mainly Fuc a1→2Gal, β-pNP with its isomers fucosylated at 0-3 or 0-6 of the sugar moiety. The three products were obtained in a ratio of 58: 22 : 20 and in 40.6% overall yield based on the donor added. Replacement of p-nitrophenyl R-D-glucopyranoside by Gal β-pNP resulted in a (1→3) -linked product as the main transfer product along with (1→2) -, (1→4) -, and (1→6) -linked isomers. With p-nitrophenyl β-lactoside acceptor, fucosylation occurred at 0-2', 0-3', and 0-6' of the Gal residue of the acceptor, but the regioselectivity was much lower than that of Gal R-pNP, while the enzyme catalyzed the formation of (1→3) - and (1→4) -linked products with p-nitrophenyl 2-acetamido-2-deoxy-β-D-glucopyranoside acceptor.
Conditions of acid hydrolysis for the preferential liberation of L-arabinose from corn fiber, a co-product of corn wet-milling processes, were investigated for the purpose of studying the production of L-arabinose. Prior to hydrolysis, starch was removed from the fiber by treatment with a-amylase. L-Arabinose was liberated rapidly at the beginning of hydrolysis and then slowed when the yield reached 12-13%. Conversely, the liberation of D-xylose was slow but linearly increased to more than 20% yield. Approximately 50 to 60% of L-arabinose in the destarched corn fiber (DSCF) was preferentially released with 0.2 N oxalic acid or 0.1 N sulfuric acid at 100° for 3 h. The ratio of Larabinose to D-xylose released was characteristic by the kind of acid used. Oxalic acid was the best for the production of L-arabinose, and hydrochloric acid was good for the production of D-xylose. Oligosaccharides were also produced in these hydrolyses. The amounts and degree of polymerization (DP) of the oligosaccharides yielded with 0.1 and 0.4 N oxalic acid at 100° for 1 h were 43%, DP 15.8, and 38%, DP 7.9, respectively. The suitable conditions so far examined for the preferential liberation of L-arabinose were hydrolysis with 0.3-1.0 N oxalic acid at 100° for 1 h, which produced 15% (62% of all L-arabinose in DSCF) L-arabinose. The yields of L-arabinose, D-xylose and soluble oligosaccharides could be controlled by the conditions of hydrolysis.
The action of cyclodextrin glucanotransferase (CGTase) on clinical dextran was demonstrated under the reaction conditions of high concentrations of enzyme and substrate. CGTase showed noticeable affinity to Sephadex G-15 gel, and lower but definite hydrolysis reaction of dextran compared with soluble starch was kinetically evaluated. CGTase seemed to cause the molecular disproportionation of dextran, which was suggested by the product analysis after ethanol fractionation of the reaction mixture. The action of the CGTase on dextran reached a maximum at higher pH of 9.5 and temperature of 50°C than with soluble starch as a substrate. Moreover, the addition of surfactant, SDS, or acceptor molecule, such as methyl α-glucoside, greatly affected the CGTase reaction. Changes in molecular weight of the dextran indicated that a clear difference in molecular weight distribution of CGTase-treated dextran had occurred, although the increase in reducing sugar was very small. That is, compared with the dextran (Mw 63, 000), both lower (Mw 10, 000) and higher (more than Mw 500, 000) molecular weight products were obtained. These results strongly suggested evidence for the action of CGTase on α-1, 6-linked dextran.
Structurally modified dextran was produced by the action of cyclodextrin glucanotransferase (CGTase) on clinical dextran. The dormant activity of CGTase was further confirmed by using the enzyme preparation from a different source. Although an increase in reducing sugar in the reaction mixture was small, a clear difference in the molecular weight distribution of CGTase-treated dextran was observed, as in previous experiments. Therefore the susceptibility of CGTases on dextran was verified with the other origin of CGTase. CGTase-treated dextran showed a higher interaction with Con A and fluorescent reagent, 6-p-toluidinylnaphthalene-2-sulfonate. The susceptibility of CGTasetreated dextran to isoamylase and glucoamylase varied significantly according to the reaction temperatures for the CGTase action. NMR-HMQC and methylation analyses both indicated additional occurrence of α-1, 4-branch points in the dextran molecule, which opposed the knowledge of sole branch point of -1, 3-linkages in the dextran. CGTase action seemed to increase the content of α-1, 4-branch points in the CGTase- treated dextran by introducing the cleaved fragments as the new branch into the back bones of α-1, 6-linkages. These results suggested that CGTasetreated dextran had increasing amounts of α-1, 4-branch points, which caused the structural changes demonstrated by the above analysis.
The action of cyclodextrin glucanotransferase (CGTase: EC 188.8.131.52) on pullulan was examined. A poor susceptibility of CGTase to pullulan was enhanced by increasing the substrate and enzyme concentrations. In spite of a small increase in reducing sugar, large changes in the molecular size of pullulan were observed especially in high-molecular weight pullulan PF30 (Mw 283, 000). These results indicated that a disproportionation activity of CGTase worked predominantly for the reconstruction of pullulan. The product pullulans showed different responses from pullulan when the interaction with the fluorescent reagent and hydrolysis with isoamylase and glucoamylase were compared. Structural analyses of product pullulans by two-dimensional NMR, HMQC, and methylation indicated that CGTase introduced a-1, 4-branch points at the nonreducing side of maltotriosyl units in pullulan molecule yielding, just like α-1, 6-branch points on the linear back bones of α-1, 4-linkages.
An acidic xylan in the 24% KOH extract of jojoba (Simmondsia chinensis) hulls was isolated and characterized by methylation analysis and enzymatic degradation studies. The results suggested that jojoba hull-acidic xylan had a linear chain of β- (1→4) -D-xylosyl residues in the backbone, about 13% of which were branched at the 0-2 position, with 4-0-methyl-α-D-glucopyranosyluronic acid residues.
Chikubu et al. (1985) proposed the palatability estimation formula of rice by using sensory overall acceptance and 21 physicochemical properties of 34 varieties. The palatability estimation formula consists of five variables: protein content, maximum viscosity, minimum viscosity, breakdown, and starch-iodine blue value. Breakdown measured with a Brabender Visco-Amylograph is defined as the difference between maximum and minimum viscosities. Therefore the formula has a multicollinearity problem. The best regression model using Chikubu et al. data was determined by the AIC statistic, multicollinearity detection, and cross-validation. The best model was as follows: y = -0.165 x3 -0.00424 x7 +0.120 x12 -8.84 x14 -O.313 (R2 =0.695), where y is the sensory overall acceptance, x3 is the protein content, x, is the minimum viscosity, x12 is the expanded volume of the cooking quality test, and x14 is the starch-iodine blue value. The correlation of the calibration data set using 34 varieties between the best model predicted values and the actual values was 0.83, and that of the cross-validation data set removing one from 34 varieties was 0.75.
The effects of weather conditions on a-amylase activity and its isozymes at maturity were investigat-ed in the three winter wheat (Triticum aestivum L.) varieties of Chihokukomugi (susceptible to pre-harvest sprouting), Kitakei-1354 (tolerant) and Lancer (tolerant) using environment cabinets. The results were: 1) In Chihokukomugi, wheat grains which were exposed to cool and wet conditions (20°C/10°C and from 80 to 100% relative humidity) at the early and middle stages of ripening exhibited relatively high α-amylase activity, due to Amy-2 isozymes, in the absence of germination (RPA: retention of pericarp α-amylase). Under cool and wet conditions in the late stage of ripening, grains germinated at maturity and with high p1 isozymes of Amy-1 were activated (PrMS: pre-maturity sprouting α-amylase). 2) Since Kitakei-1354 showed a dull response to weather conditions during the ripening stage, low α-amylase activity and little germination were observed consistently. 3) In Lancer, Amy-1 was activated in the absence of germination (PMAA: pre-maturity α-amylase) under not only cool and wet conditions but also under hot and dry conditions. 4) Accordingly, three pathways (RPA, PrMS and PMAA) of α-amylase formation at maturity were observed in Hokkaido. Since certain varieties like Lancer often exhibited high α-amylase activity at maturity in spite of high tolerance to pre-harvest sprouting, α-amylase activity at maturity as well as dormancy of wheat grain was an important criteria. Further investigations are needed to clarify the precise environmental factors which induce PMAA formation.
Hyaluronan oligosaccharides were analyzed using high-performance anion-exchange chromatogra-phy with pulsed amperometric detection (HPAEC-PAD) . The procedure invalves the separation of hyaluronan oligosaccharides on an anion-exchange column, CarboPac PA-1, using alkaline eluants. A gradient is made using these two solutions; solution A (100 mM sodium hydroxide) and solution B (100 mM sodium hydroxide/1.5 M sodium acetate), eluted at 1 mL/min. The unit resolution of hyaluronan oligomers could be achieved up to at least 20 disaccharide units through HPAEC-PAD. Furthermore, integrated pulsed amperometry detected only -40 pmol of hyaluronan oligosaccharide. This analysis system was easily used for the separation and quantitative analysis of hyaluronan oligosaccharides, and applied to the determination of the time course of hyaluronidase digestion of hyaluronan.