A review with 73 references (1954-1968) including 22 references of Kawamura, Tada, et al. The legumes studied are the peanut, broad bean, pea, adzuki bean, mung bean, kidney bean, asparagus bean, hyacinth bean, sword bean, soybean, and Yokohama bean. Topics include physical properties of starch granules, fractionation and determination of amylose and amylopectin, and biochemical studies on starch metabolism. Legume starches were divided into two groups according to granule size, a (large) and b (small), according to amylose content, α(high) and β(low), and according to the Brabender amylogram, A (nonviscous paste) and B (viscous paste). All starches belonging to A had large granules (a) and high amylose content (α), while most of starches of B had small granules (b) and low amylose content (β). The starches from mature broad beans and peas belonged to a and α, while those from immature ones belonged to b and β . In broad beans and peas, appositive growth of starch granules was presumed.

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A comparison of phosphorylative agents is made to determine their usefulness for producing phosphate esters of corn amylose, corn amylopectin and a mainly 1→6 linked dextran. Orthophenylene and biscyclopropylcarbinyl phosphorochloridates, and bismorpholenophos- phorobromidate produce esters with degrees of substitution (D.S.) of 0.7-1.0. However, use of tetrapolyphosphate as the trialkyl amine salt readily produces an ester of D.S. 1.0 or higher without significant degradation of the polysaccharides . This easy and recommended procedure yields phosphate esters of high viscosity . Because of charge repulsions it is difficult to produce esters significantly above 1.0 D.S. Below this level both primary and secondary alcohol functions are phosphorylated . The phosphate ester groups are remarkably stable to alkaline hydrolysis but are slowly hydrolyzed by acid.

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1) Calorimetric studies on the enzymic hydrolyses of maltose, phenyl α-maltoside, isomaltose, maltotriose, panose and amylose have been made and the heats of hydrolysis of the α-1, 4 and α-1, 6 glucosidic linkages have been evaluated. 2) The heats of hydrolysis of α-l, 4 and α-1, 6 glucosidic linkages has been found to be approximately equal in their absolute magnitudes, but opposite in sign for the two linkages. It has also been found that the heat of hydrolysis of sugar compounds is obtainable as an ad ditive function of the thermal data of individual linkages to be hydrolyzed . 3) Calorimetric studies on the hydrolyses of starches and glycogens from various sources have been made and the α-1, 4 glucosidic linkage content in the respective sample has been determined by using the thermal data obtained for the two linkages. 4) Combining the data for linkage content with those concerning the amylose content of the starches determined by the amperometric titration method, the average length of unit chain of the amylopectin component has been evaluated. The average length of unit chain of the glycogens has also been evaluated. 5) The calorimetric method has been applied to the determination of the α-1, 4 gluco sidic linkage content in two kinds of sweet potato starch (i.e., Normn-1 and Okinawa-100) isolated at two different stages of development. It has been found that the sample isolated on October 31 (1953) had a higher value for α-1, 4 glucosidic linkage content than the sample isolated on August 6 (1953) for both the two sweet potato starches. The increase in α-1, 4 glucosidic linkage content has been found to be due to both the increases in amylose content and in average unit chain length of amylopectin component.

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The action patterns of enzymes, which are able to hydrolyze α-1, 6 glucosidic linkages at the branching points in starch-type polysaccharides, are reviewed.
The enzyme of this type found first was the yeast isoamylase, which was proved to split the branching points in amylopectin, glycogen, and dextrins. Similar enzymes were found later in higher plants and bacteria. However, actions of all these enzymes were not identical, as every enzyme had its own substrate specificity.
There are several other enzymes which can act on the branching points in low molecular weight dextrins but not in native amylopectin or glycogen. An enzyme, amylo-1, 6-glucosid ase found in higher animals, is specific to phosphorylase limit dextrin. Its action mechanism is not fully established, so far the fact known is the involvement of a transglucosylation in the breakdown of this limit dextrin.
In addition to enzymes mentioned above, glucoamylases of microbial origin are able to split α-1, 6- as well as α-1, 4-glucosidic linkages in branched polysaccharides, to attain complete degradation into glucose.
Differences in the actions of these enzymes were discussed, enzymes were classified according to their specificity, and summarized in a table.

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Two aspects of experiments, in vivo and in vitro, are described in this review . In in vitro experiments, the crystallization of starch was studied on some model systems using amylodextrin. The results suggested that the crystalline structure of a starch granule was dependent on external temperature and microenvironment of cellular location developing a starch granule and it was in keeping with results of the follwing in vivo experiments. In in vivo experiments, the temperature of soybean seedlings, potato tubers, sweet potato roots and rice ears was controlled at constant during starch accumulation period using some devices. The following changes were noted in respective starches by elevation of environment temperature. (1) Pasting temperature decreased considerably in all the test series. (2) Maximum viscosity (amylogram) decreased in potato and sweet potato, increased in rice and was approximately constant in soybean seedlings (cotyledon) . (3) a-Amylase susceptibility of raw granules and (4) content of bound phosphate were decreased. (5) Amylose content was decreased appreciably in rice and slightly in soybean seedling hypocotyls and was constant in potato and soybean seedling cotyledons. (6) Crystalline type shifted from B or C type toward A type in soybean seedlings and sweet potato and was constant in potato (B type) and rice (A type). From these results, a new day-night rhythm structure in a native starch granule was suggested and relations of the structure to the property were discussed .

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A model experiment was performed to simulate the process of precipitation of starch molecules in plastids. This suggested the presence of a soluble form of ADP -glucose α-1, 4-glucan-α-4-glucosyltransferase (starch synthetase) in spinach chloroplasts . The enzyme was purified in order to use it as chain elongator in a system for starch granule formation in vitro, which is to be constructed by well-characterized enzymes. It was found that the spinach enzyme catalyzes the formation of a long chain of α-1, 4-linked glucose units.

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The review contains four sections; 1) starch granule-bound UDP-glucose starch glucosyl transferase deficiency in waxy maize, 2) the proportionality of bound transferase activity with number of Wx alleles for the endosperm and a comparison of transferase from embryo and endosperm, 3) ADP-glucose pyrophosphorylase dificiency in shrunken-2 and brittle-2 mutants, 4) phosphorylase I, II, and III in maize endosperm. These investigations reported in this review emphasize our limited knowledge of how starch synthesis really proceeds in the endosperm of maize. At the same time, they illustrate how useful the mutant data may be in contributing to an ultimate solution.

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Recent experimental results that we have obtained on potato phosphorylase [EC 2.4. 1. 1] are summarized and discussed in comparison with those of muscle phosphorylase b. They contain: 1) Purification and crystallization, 2) de novo Synthesis, 3) Molecular weight and amino acid composition, 4) Bound pyridoxal phosphate, 5) Circular dichroism, 6) Chemical modification. Although potato phosphorylase differs from muscle phosphorylase b in deter-mining enzyme activity, their molecular properties resemble each other in many respects which include molecular weight, amino acid composition, content and binding of pyridoxal phosphate, higher structure observed through circular dichroism, and specific amino acid residues directly involved in activity. It is also shown that primer is an absolute requirement for the synthesis of α-1, 4-glucan and no de nova synthesis occurs by phosphorylase.

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In enzymatically liquefied and subsequently saccharified starch solution, some materials often remained insoluble. They contain starch particles which are extremely hard to be solubilized. When their content is high, the resulting saccharified liquid is difficult to be filtered and further purified. This difficulty is a serious concern in commercial production of dextrose. A part of the insoluble starch particles is formed during the liquefaction of starch. Lower temperature than 85°C in liquefaction favors formation of the insoluble starch particles. The other part of the insoluble starch particles comes from the original raw materials. Their contents differ from species to species; the lowest in potato starch and the highest in corn starch. It is also observed that the insoluble starch particles are formed upon heatmoisture treatment of starch. These insoluble starch particles are presumably composed of straight chain molecules of starch.

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Research on physicochemical quality of rice was carried out for some past dozen years in Food Research Institute, Ministry of Agriculture and Forestry. In order to compare the quality of japonica rice with that of indica rice, several physicochemical properties of rice including rheological properties of starch were investigated, and characteristics of japonica rice were recognized as follows; round shape, low amylose content, low pasting temperature of starch, low rigidity of starch paste, small water uptake ratio and small expanded volume in cooking qualities. On the other hand, series of cultivation experiments were conducted at several experimental stations located from northeast to southwest in the Japan islands with a single clone of rice, and starch properties, cooking qualities and inorganic constituents were measured on these samples. As the results of these experiments, the difference of rice quality due to environment and cultivated condition was recognized even in the Japan islands. Moreover, relations among characteristics of starch and cooking qualities were studied . At the same time, relation between sensory evaluation of cooked rice and physicochemical properties of rice was also studied. As the results, correlation between sensory evaluation and some factors was most significant. It is thought that these factors form contact feeling of cooked rice and give a great influence to the Japanese palatability evaluation of rice.

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The fragmentation analysis of polysaccharides which involves the controlled acid hydrolysis of a polysaccharide and the isolation and characterization of the oligosaccharide frag ments by charcoal chromatography was applied to waxy rice amylopectin and resulted in isolation of two panose isomers, isopanose (6-α-maltosyl glucose) and a trisaccharide which might be tentatively called "branched trisaccharide" (4, 6-di-α-glucosyl glucose). Isolation of the latter afforded a direct evidence forr the branched structure of amylopectin .

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Starch, amylopectin, carboxymethyl-starch and-cellulose, pectin, and alginic acid were found to be susceptible to degradation or depolymerization at ordinary temperature in the presence of free radical producing systems containing hydrogen peroxide and the synergist such as ascorbic acid, erythorbic acid, or ferrocyanate. Degree of depolymerization of amylopectin in terms of viscosity reduction was found to be proportional to the levels of free radical producing agents used.

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In order to explain the solution characteristics of such highly branched natural polymers as amylopectin, dextan etc., a semi-empirical method is proposed. This method depends on the approximate relations that the branching factor of the radius of gyration g is proportional to m^-1/2 when the number of branching m are small, and to m-1/2 when m are large, and that the branching factor of frictional coefficient g_f is nearly equal to g^1/3 . As for the branching factor of intrinsic viscosity g', having examined the exponent of the intrinsic viscosity -molecular weight relationship, and the extension of the Fixman and Ptitsyn type equations of excluded volume effect for a linear polymer to a branched polymer, the assumption of g'=g gives the best results. From these extended equations and the similar equations for the frictional coefficient, the length of subchain can be estimated . By using the above relations, the molecular wght and g of a branched polymer can be obtained from s₀ and [n]. The above results were applied to amylopectin to analyze s₀ and [n] and then to obtain the relation between m and molecular weight. The high molecular weight amylopectin (more than 5×10⁶, approximately) is "native" amylopectin, as the linear relation is obtained between m and molecular weight, and the length of a subchain of amylopectin corresponds to about 20 of glucose units.

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Alpha-amylase adsorption on raw starch and its relation to raw starch digestion were investigated. Four kinds of α-amylases-pancreatic, malt, fungal, and bacterial amylaseswere used. The relation of digestion of raw starch by a-amylases to adsorption of the enzyme was complicated and it was dependent on the specific enzyme, its concentration, time of action and on the specific starch involved. The adsorption of the enzyme on raw starch was rapid and was desorbed at a decelerating rate with time and was similar to the digestion activity curve.

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α(1→4) glucan glucosyl transferase (starch synthetase) from spinach leaveen-abstract= It was found that a partially purified preparation of ADP-glucose-s is bound specifically with the amylose molecule. The adsorption of the starch synthetase with starch granules prepared from nonglutinous rice seeds was quite strong, while the binding reaction of the starch granules from glutinous rice seeds was the least. The specific adsorption of the soluble enzyme with amylose has been studied under various experimental conditions. The reaction was found to be weakest at an acid pH, around pH 5.0, and maximal at neutral pH ranges. At temperatures higher than 25°C, less enzyme molecules were bound to amylose. By determining the time effect of the enzyme adsorption to the amylose molecule, it was found that the longer the contact of the soluble enzyme with amylose the stronger the binding of enzyme with amylose. However, from the fact that the substrate specificity of the chloroplastic soluble starch synthetase did not change after the binding with the amylose molecule it can be suggested that the starch synthetase of different plant origins may exhibit the organ specific substrate utilization.

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The relationship between the subunit structure and the catalytic activity of crystalline rabbit skeletal muscle phosphorylase b was studied by comparing the dissociation-association state of the enzyme at various concentrations of different buffers (determined by the sedimentation coefficient in the analytical ultracentrifuge) and the co-operativity of the enzyme with 5'-AMP (determined by the catalytic activity in the presence of various concentrations of added 5'-AMP). Sodium ?A-glycerophosphate, ammonium citrate, and imidazole citrate buffers, all at pH 6.5, were used in these experiments. The characteristic features of these buffers on the subunit structure and the catalytic activity of the enzyme were described. When the protein concentration was rather high (7.0 mg/ ml) and in the presence of a sufficient amount of added 5'-AMP, phosphorylase b was found to be present as a tetrameric form irrespective of the buffer used. Also, it was suggested from the analysis of the data presented in this paper that there may be only one active state of phosphorylase b, that is a dimeric form, when the enzyme is actively synthesizing glycogen in the presence of both 5'-AMP, an allosteric activator, and the substrates (a-n-glucose-l-phosphate and glycogen).

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