Inhibition of sweet potato glucose 6-phosphate dehydrogenase by NADPH2 and ATP

NADPH₂ and ATP competitively inhibit sweet potato glucose 6-phosphatedehydrogenase with NADP and glucose 6-phosphate (G6P), respectively.At pH 8.0, a Lineweaver-Burk plot of the reciprocal rate againstreciprocal G6P concentration was concave downwards in the presenceand absence of ATP, whereas a double reciprocal plot followedthe Michaelis-Menten relationship at pH 7.0, irrespective ofthe presence of ATP. Many of the other metabolic intermediatestested had no effects on the enzyme reaction. ¹ This paper constitutes Part 96 of the Phytopathological Chemistryof Sweet Potato with Black Rot and Injury. ² Present address: Institute of Applied Microbiology, Universityof Tokyo Bunkyo-ku, Tokyo 113. (Received October 20, 1971; )     

Some Problems in the Assay Method of HMG-CoA Reductase Activity in Sweet Potato in the Presence of Other HMG-CoA Utilizing Enzymes

In addition to HMG-CoA reductase, another HMG-CoA utilizing enzyme is present in the Mt fraction of sweet potato root tissue and its activity interferes with the assay to HMG-CoA reductase activity.     

The Incorporation of Leucine-U-14C into Ipomeamarone

1. It was demonstrated by silica gel thin layer chromatography that leucine-U-¹⁴C was incorporated into furanoterpenes, e. g. ipomeamarone, in sweet potato root tissue infected by Ceratocystis fimbriata.

2. Further proof for ipomeamarone synthesis from leucine-U-¹⁴C was obtained by the constancy of the specific radioactivity of ipomeamarone semicarbazone through repetitive crystallization.

3. The synthetic pathway of ipomeamarone from leucine was found to be connected with the synthetic pathway from acetate at least at some steps.

4. Leucine-U-¹⁴C was incorporated into both saponifiable and non-saponifiable materials in the same way as acetate-2-¹⁴C.     

Electrophoretic Study of Protein Metabolism in Sweet Potato Infected with Ceratostomella fimbriata

It was shown in previous papers that in sweet potato infected with Ceratostomella fimbriata, there occurred metabolic activations such as respiratory increase, polyphenols production, protein synthesis and organic phosphate accumulation. In this report on an electrophoretic experiment, forming a part of those studies, it is stated that the pattern of the protein components in the sound part, adjacent to the infected part of sweet potato attacked by the pathogen differs from that of sound sweet potato.     

Terpenoid Induction in Sweet Potato Roots by Cyclic-3′, 5′-Adenosine Monophosphate

The bar-headed goose, a specialized high-altitude species, has a capacity for high oxygen uptake from a hypoxic environment. It thus has a higher oxygen affinity than other bird species of lower-altitude environments. Oxygen affinity is determined by molecular structures and genetic mutations of hemoglobin (Hb), which can also influence the coordinating structures and dynamics of oxygen-Hb. To explore the structural differences in Hbs as between high and low altitude species, photolysis dynamic parameters, including quantum yield, enthalpy, and conformational volume changes in carboxy-Hbs (HbCO) for the bar-headed goose and low altitude counterparts (the Chinese goose and chicken) were investigated by the laser pumping-probing technique and photoacoustic calorimetry. Comparing the photolysis results for HbCO of the three species, the enthalpy and conformational volume changes of the bar-headed goose were much smaller than those of the others, although the quantum yields of all three species are similar. To explain the possible mechanisms of these differences, modifications of salt bridges and key residue mutations at the α β subunit interfaces of the proteins are described and discussed briefly.     

Isolation of Possible Intermediate of Chlorogenic Acid Biosynthesis in Sweet Potato Root Tissue

Thienodolin, a new plant growth-regulating substance, was isolated from the fermentation broth of a streptomycete strain identified as Streptomyces albogriseolus.

The active principle was extracted with ethyl acetate and purified by silica gel column chromatography and preparative HPLC. The substance showed growth promoting activity with 1.2 × 10^?6–1.2 × 10^?5 M treatment to rice seedlings, and inhibitory activity with 4.0 × 10^?5 M treatment.     

Detection and analysis of translation elongation factor 3 genes from various yeasts.

Yeast translation requires a unique elongation factor, EF-3. However, information about EF-3 genes has been limited to only a few yeast species. Here, we developed a PCR-based system to detect the EF-3 genes specifically, and identified EF-3 gene fragments from various yeast species in which EF-3 genes have not yet been found.     

Increase of Mitochondrial Fraction in Sweet Potato Root Tissue after Wounding or Infection with Ceratocystis fimbriata

The acid-insoluble nitrogen content, lipid content, and cytochrome oxidase activity in the mitochondrial fraction are found to increase during incubation of slices of sweet potato (Ipomoea batatas) root tissue. These increases appear to be related to an increase in the number of the mitochondrial particles. The increase in the mitochondrial fraction is not accompanied by an increase in cell number. The nitrogen content in the mitochondrial fraction increases prior to the changes in the activity of cytochrome oxidase and lipid content. The increase in the numbers of the mitochondrial particles lags behind the increase in the cytochrome oxidase activity. Such findings are also found in the tissue infected by Ceratocystis fimbriata.