Cloning and sequence analysis of cDNA encoding active phosphoenolpyruvate carboxylase of the C4-pathway from maize.

A recombinant clone, pM52, containing cDNA for maize phosphoenolpyruvate carboxylase (PEPCase, EC 4.1.1.31) was isolated from a maize leaf cDNA library constructed using an expression vector in Escherichia coli. The screening of the clone was conveniently performed through its ability to complement the phenotype (glutamate requirement) of PEPCase-negative mutant of E. coli. The enzyme encoded by this clone was identical with the major PEPCase in maize, a key enzyme in the C4-pathway, as judged from its allosteric properties and immunological reactivity. The cloned cDNA (3093 nucleotides in length) contained an open reading frame of 2805 nucleotides, the 3'-untranslated region of 222 nucleotides and the poly(dA) tract of 64 nucleotides. The deduced amino acid sequence (935 residues) of the enzyme showed higher homology with that of an enterobacterium, E. coli (43%) than that of a cyanobacterium (blue-green alga), Anacystis nidulans (33%).     

Lysine proximity significantly affects glycation of lysine-containing collagen model peptides

Advanced glycation end products (AGE) are known to cause diabetes complications in hyperglycemia patients. In this study we prepared hetero-trimers of collagen model peptides comprising Ac-(Pro-Hyp-Gly)(5)-Pro-Lys-Gly-(Pro-Hyp-Gly)(5)-Ala-NH(2) (4) and Ac-(Pro-Hyp-Gly)(11)-Ala-NH(2) (5) to investigate the clustering effect of lysine on AGE formation. The formation rate of carboxymethyllysine over several months was determined for the mixtures of peptides 4 and 5 at (3:0), (2:1) and (1:2) in the presence of glucose. The contents of carboxymethyllysine were significantly enhanced for (3:0) and (2:1) as compared with (1:2), suggesting that the proximity of lysine residues in the trimers accelerated formation of the AGE. Furthermore, a lysine dimerization moiety (GOLD) was identified for the first time from AGEs of glucose origin, which implied the significance of GOLD in oligomerization of collagens and other long-life proteins.     

Steatitis in egrets and herons from Japan

More than 70 egrets and herons were found sick or dead at an agricultural water reservoir in Kanagawa Prefecture, Japan between September and October 2008. The birds showed weakness, lethargy, and inability to fly before death. Postmortem findings included large amounts of firm subcutaneous and cavitary fat comprised of necrotic adipose tissues with infiltrates of heterophils and macrophages. The birds were diagnosed with steatitis on the basis of the gross lesions and histopathology. Egrets with steatitis had low blood levels of vitamin E. High counts of cyanobacteria (Microcystis aeruginosa) were found in the reservoir concurrent with the outbreak of steatitis. No microcystin was detected in the reservoir water or the livers from the egrets. This is the first report of steatitis in wild birds in Japan.     

Isolation and Restriction Mapping of a Pseudomonas Plasmid

The effects of the injection of a large amount of N¹ -methylnicotinamide (MNA) (500 mg per kg body weight) on the ratio of N¹ -methyl-4-pyridone-3-carboxamide (4-py) to N¹ -methyl-2-pyridone-5- carboxamide (2-py) excretion, and the activities of 2-py and 4-py forming MNA oxidases were investigated in rats. The injected MN A was excreted very rapidly into the urine; 46 % of the dose was excreted from 0~3hr post-injection, 15% from 3~6hr, 6% from 6~9hr and 1.5% from 9~ 12hr. The ratio of 4-py to 2-py also decreased rapidly; the ratio being about 0.6, 0.4, 0.4 and 0.6 from 0~3hr, 3~6hr, 6~9hr and 9~ 12hr post-injection, respectively. This ratio then recovered rapidly; being about 2, 5.5, 8.5 and 9.7 from 12~24 hr, 24 ~48 hr, 48~72 hr and 72 ~96 hr post-injection, respectively. The normal range of 4-py to 2-py excretion ratio is 8~14. So, this ratio returned to a normal level by day 3 post-injection. The rats were killed 5 hr after the MNA injection. At this time (the lowest ratio was observed around this time), the activities of 2-py and 4-py forming MNA oxidases in the injected group were 59 % and 11 % of the normal levels, respectively. Therefore, it was found that the decreased ratio of 4-py to 2-py excretion with the MNA injection was mainly due to the higher inhibition of the 4-py forming MNA oxidase than of the 2-py forming MNA oxidase by the MNA injection.     

Chemoenzymatic synthesis and application of glycopolymers containing multivalent sialyloligosaccharides with a poly(L-glutamic acid) backbone for inhibition of infection by influenza viruses

Highly water-soluble glycopolymers with poly(alpha-L-glutamic acid) (PGA) backbones carrying multivalent sialyl oligosaccharides units were chemoenzymatically synthesized as polymeric inhibitors of infection by human influenza viruses. p-Aminophenyl disaccharide glycosides were coupled with gamma-carboxyl groups of PGA side chains and enzymatically converted to Neu5Acalpha2-3Galbeta1-4GlcNAcbeta-, Neu5Acalpha2-6Galbeta1-4GlcNAcbeta-, Neu5Acalpha2-3Galbeta1-3GalNAcalpha-, and Neu5Acalpha2-3Galbeta1-3GalNAcbeta- units, respectively, by alpha2,3- or alpha2,6-sialytransferases. The glycopolymers synthesized were used for neutralization of human influenza A and B virus infection as assessed by measurement of the degree of cytopathic inhibitory effect in virus-infected MDCK cells. Among the glycopolymers tested, alpha2,6-sialo-PGA with a high molecular weight (260 kDa) most significantly inhibited infection by an influenza A virus, strain A/Memphis/1/71 (H3N2), which predominantly binds to alpha2-6 Neu5Ac residue. The alpha2,6-sialo-PGA also inhibited infection by an influenza B virus, B/Lee/40. The binding preference of viruses to terminal sialic acids was affected by core determinants of the sugar chain, Galbeta1-4GlcNAcbeta- or Galbeta1-3GalNAcalpha/beta- units. Inhibition of infection by viruses was remarkably enhanced by increasing the molecular weight and sialic acid content of glycopolymers.     

The localization and phosphorylation of p47 are important for Golgi disassembly-assembly during the cell cycle

In mammalian cells, the Golgi apparatus is disassembled at the onset of mitosis and reassembled at the end of mitosis. This disassembly-reassembly is generally believed to be essential for the equal partitioning of Golgi into two daughter cells. For Golgi disassembly, membrane fusion, which is mediated by NSF and p97, needs to be blocked. For the NSF pathway, the tethering of p115-GM130 is disrupted by the mitotic phosphorylation of GM130, resulting in the inhibition of NSF-mediated fusion. In contrast, the p97/p47 pathway does not require p115-GM130 tethering, and its mitotic inhibitory mechanism has been unclear. Now, we have found that p47, which mainly localizes to the nucleus during interphase, is phosphorylated on Serine-140 by Cdc2 at mitosis. The phosphorylated p47 does not bind to Golgi membranes. An in vitro assay shows that this phosphorylation is required for Golgi disassembly. Microinjection of p47(S140A), which is unable to be phosphorylated, allows the cell to keep Golgi stacks during mitosis and has no effect on the equal partitioning of Golgi into two daughter cells, suggesting that Golgi fragmentation-dispersion may not be obligatory for equal partitioning even in mammalian cells.     

6-Hydroxypelargonidin glycosides in the orange-red flowers of Alstroemeria

Two 6-hydroxypelargonidin glycosides were isolated from the orange-red flowers of Alstroemeria cultivars, and determined to be 6-hydroxypelargonidin 3-O-(beta-D-glucopyranoside) and 3-O-[6-O-(alpha-L-rhamnopyranosyl)-beta-D-glucopyranoside], respectively, by chemical and spectroscopic methods. In addition, five known anthocyanidin glycosides, 6-hydroxycyanidin 3-malonylglucoside, 6-hydroxycyanidin 3-rutinoside, cyanidin 3-malonylglucoside, cyanidin 3-rutinoside and pelargonidin 3-rutinoside were identified in the flowers.     

Podophyllotoxin and nocodazole counter the effect of IKP104 on tubulin decay

Tubulin, the subunit protein of microtubules, undergoes a time-dependent loss of functional properties known as decay. We have previously shown that the drug 2-(4-fluorophenyl)-1-(2-chloro-3,5-dimethoxyphenyl)-3-methyl-6-phenyl-4(1H)-pyridinone (IKP104) accelerates decay, but that in the presence of colchicine, IKP104 becomes a stabilizer of tubulin. To see if this is due to conformational effects specific to colchicine or simply to occupancy at the colchicine site, we examined the effects of nocodazole and podophyllotoxin, two well-known competitive inhibitors of colchicine for binding to tubulin, on IKP104’s acceleration of decay. We found that podophyllotoxin abolished IKP104’s accelerating effect and, like colchicine, turned it into a stabilizer of tubulin. Nocodazole’s effects were similar to those of podophyllotoxin and colchicine, in that it abolished IKP104-induced enhancement of decay; however, in the presence of nocodazole, IKP104 caused little or no stabilization of tubulin. Since colchicine, nocodazole, and podophyllotoxin have very different interactions with tubulin, but all inhibit the IKP104-induced enhancement of decay, our findings suggest that this inhibition arises from occupancy of the colchicine site rather than from a direct conformational effect of these two drugs.     

Substrate Specificity of α-Glucosidase II in Rice Seed

The substrate specificity of rice α-glucosidase II was studied. The enzyme was active especially on nigerose, phenyl-α-maltoside and maltooligosaccharides. The actions on isomaltose and phenyl-α-glucoside were weak, and on sucrose and methyl-α-glucoside, negligible. The α-glucans, such as soluble starch, amylopectin, β-limit dextrin, glycogen and amylose, were also hydrolyzed.

The ratio of the maximum velocities for hydrolyses of maltose (G₂), nigerose (N), kojibiose (K), isomaltose (I), phenyl-α-maltoside (?M) and soluble starch (SS) was estimated to be 100: 94.4: 14.2: 7.1: 89.5: 103.1 in this order, and that for hydrolyses of malto-triose (G₃), -tetraose (G₄), -pentaose (G₅), -hexaose (G₆), -heptaose (G₇), -octaose (G₈), and amyloses ( and ), 113: 113: 113: 106: 113: 100: 106: 106. The Km values for N, K, I, ?M and SS were 2.4 mm, 0.58 mm, 20 mm, 1.6 mm and 5.0 mg/ml, respectively; those for G₂, G₃, G₄, G₅, G₆, G₇, G₈, and , 2.4 mm, 2.2 mm, 2.1 mm, 1.5 mm, 1.0 mm, 1.1 mm, 0.95 mm, 1.5 mm and 1.1 mm.

Rice α-glucosidase II is considered an enzyme with a preferential activity on maltooligosaccharides.