M. Harada

Inorganic Pyrophosphatase Activity of Purified Bovine Pulp Alkaline Phosphatase at Physiological pH

At physiological pH, the hydrolytic activity of purified bovine pulp alkaline phosphatase toward phosphorus compounds was observed to be in the order of inorganic pyrophosphate > β-glycerophosphate > phosphorylcholine > p-nitrophenylphosphate > glucose-6-phosphate. Optimum pH of the enzyme toward inorganic pyrophosphate was shown to be 8.5, with around 60% of the activity at pH 7.5. The activity was increased by the addition of Mg2+, but a different pattern of activation was observed between pH 7.5 and 8.5.

Peptidase activity of glycylprolyl β-naphthylamidase from human submaxillary gland

Abstract Peptidase activity of glycylprolyl β-naphthylamidase purified from human submaxillary glands was studied. The enzyme hydrolyzed the peptide bond between N-terminal glycylproline and the following amino acids or peptides including alanine, leucine, glutamic acid and leucylglycylproline, except proline and hydroxyproline. However, glycylprolylhydroxyproline did not show any inhibitory effect on glycylprolyl β-naphthy-lamidase activity.

Analysis and identification of human parotid salivary proteins by micro two-dimensional electrophoresis and Western-blot techniques

Using this method, without denaturing agents, over 60 protein components in 2 microliter (about 4 micrograms of protein) of unconcentrated parotid saliva could be detected. After two-dimensional separation, the spots of albumin, secretory IgA, IgG, acid phosphatase, amylase and plasma-originating protein were identified by antibodies with the Western-blot technique.

Inactivation of tyrosine hydroxylase in rat striatum by 1-methyl-4-phenylpyridinium ion (MPP+)

We report that 1-methyl-4-phenylpyridinium ion (MPP+), the active metabolite of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), inactivated tyrosine hydroxylase (TH) when MPP+ was directly infused into the striatum. We examined both in vitro TH activity and TH content measured by an enzyme immunoassay in the rat striatum after MPP+ was administered by an in vivo brain microdialysis probe. MPP+ caused the inhibition of TH activity but did not influence TH content in the ipsilateral striatum. These results indicate that MPP+ may cause an acute inactivation of TH after continuous exposure at the high concentrations.

Hydrolysis of amino acid β-naphthylamides by aminopeptidases in the parotid gland

Die Aktivität der Aminopeptidasen in Ohrspeicheldrüsen wurde gemessen. Glycyl-Prolinβ-naphthylamid, Alaninβ-naphthylamid, Leucinβ-naphthylamid, Methioninβ-naphthylamid, und Argininβ-naphthylamid wurden von der Mikrosomenfraktion und der löslichen Fraktion schnell gespalten. Das Glycyl-Prolinβ-naphthylamid spaltende Enzym war in Ohrspeicheldrüsen in relativ grösserer Menge vorhanden. Die Aufspaltung von Glycyl-Prolinβ-naphthylamid in Glycyl-Prolin undβ-Naphthylamin wurde papierchromatographisch nachgewiesen.

Sandwich enzyme-immunoassay for dipeptidyl aminopeptidase IV in the serum of people with oral cancer

A highly-sensitive sandwich enzyme immunoassay for serum dipeptidyl aminopeptidase IV (DAP IV) was developed; its level in sera of patients with oral cancer [1.50 +/- 0.35(SD)mg/l serum] was significantly lower than in normal subjects [2.27 +/- 0.77(SD)mg/l serum].

Hypertriglyceridemia associated with Tumor Necrosis Factor-α in Hamster Cheek-pouch Carcinogenesis

We demonstrated for the first time that 9,10-dimethyl-l,2-benzanthracene (DMBA)-treated hamsters showed hypertriglyceridemia followed by cachexia. Hypertriglyceridemia is believed to be caused in part by the decreased lipoprotein lipase (LPL) activity, and by cytokines such as tumor necrosis factor (TNF)-a. In addition, TNF-a action is associated with the LPL activity. Therefore, we determined the content of triglyceride (TG), LPL, and TNF-a in the serum from DMBA-treated hamsters. Elevated TG concentration in the serum of tumor-bearing hamsters was more remarkable and preceded the increase in other lipids, whereas the activity of LPL, the key enzyme of TG metabolism in vivo, was drastically reduced. TNF-a, known as an endogenous inhibitor of LPL activity, was detected in both the sera and the extract of tumors from DMBA-treated hamsters, whereas it was not detectable in any control samples. Pre-incubation of control sera with exogenous recombinant human TNF-a resulted in a potent inhibition of endogenous LPL activity in a dose-dependent manner in vitro. Therefore, the presence of TNF-a might lead to the increase in plasma TG mediated by LPL in tumor-bearing hamsters.

Intracellular Localization of Monoamine Oxidase in Mammalian Salivary Glands

Intracellular distribution of monoamine oxidase in the submaxillary gland of the human, cat, rat, and bovine, and in the parotid gland of the bovine, were determined using kynuramine as a substrate. The excretion of the enzyme in the parotid saliva of humans was also examined by sensitive fluorometric methods.

Phosphate and insoluble protein interaction in bovine dental pulp

Abstract The phosphate-containing components of bovine dental pulp were separated into NaCl-soluble and acetic acid-soluble fractions representing 27.9 and 41.3 per cent of the material respectively. A further 19.8 per cent was found in the insoluble fraction which consisted mainly of collagen. The phosphate of this fraction was not removed by dialysis against distilled water, thus differing from the salt and acid fractions, the phosphate of which was dialysable. Digestion with proteinases released the phosphate from the insoluble fraction. Free inorganic phosphate was detected only after high-voltage electrophoresis of the protease digests.

A fluorometric study of flavins in human saliva

Abstract The concentrations of flavins in human mixed saliva and in human duct saliva from the parotid gland and the submaxillary-sublingual glands were measured by lumiflavin fluorescence assay, and found to be 8.44 ± 4.66, 1.74 ± 0.33, and 1.29 ± 0.84 m μ moles/100 ml saliva, respectively. Since the treatment of mixed saliva either by millipore filtration or by high-speed centrifugation caused a decrease of flavins, some part of the vitamin in mixed saliva may be contained in suspended matter such as bacteria or cells. When flavin mononucleotide was injected intramuscularly, a small amount of free flavins was excreted rapidly into parotid saliva. A peak of the excretion was observed between 10 and 20 min.