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Peroxidase-rich fruits and vegetables are reputed to interfere with guaiac-based fecal occult blood tests. We added horseradish peroxidase to fecal samples and tested them with Hemoccult, Hemoccult SENSA(R), and hydrated Hemoccult. Positivity rates with Hemoccult and Hemoccult SENSA decreased rapidly as the time between smearing (preparation) and development increased, whereas they remained high with hydrated Hemoccult. For samples with added blood, positivity rates did not decrease with time. When 61 volunteers were tested on a standard restriction and on a challenge diet high in plant peroxidase, no positive results occurred during standard restriction. During the challenge diet, one volunteer was positive with Hemoccult and Hemoccult SENSA when development was delayed 24 h, and no volunteers were positive when it was delayed 48 h and 72 h. However, with hydrated Hemoccult, positives occurred in 13 of 61 volunteers at 24 h, 8 of 61 at 48 h, and 5 of 61 at 72 h. Thus, peroxidase-rich plant foods do not need to be excluded from the diet with Hemoccult and Hemoccult SENSA if development is delayed for at least 48 h after smearing. A delay of this duration will not solve the problem of plant peroxidase interference with hydrated Hemoccult.

Two cDNA clones, pSoSPS1 and pSoSPS2, encoding sucrose-phosphate synthase (SPS) of sugarcane were isolated from a leaf cDNA library. Northern analysis revealed the transcript of SoSPS1 to be predominant in leaves, but that of SoSPS2 to be distributed not only in leaves but also in roots at a similar level. The transcript of SoSPS1 was markedly accumulated during greening of etiolated leaves, whereas that of SoSPS2 was constitutively expressed. These findings indicate that SPS in sugarcane is encoded by multiple genes, which show organ-specificity and are differentially regulated in response to light.

We have isolated two cDNA clones (CDES01) and 04) encoding stearoyl-acyl carrier protein desaturase (SACPD; EC 1.14.99.6) from immature sesame seeds, and have analyzed accumulation levels of the corresponding mRNAs at different stages and organs in sesame. Clone CDES01 contains an open reading frame coding for a 396-amino acid protein of 45 kDa. CDES04 encodes a partial sequence of 141-amino acids. Deduced amino acid sequences of both clones exhibit a high identity to those of other plant SACPD cDNAs. Northern blots probed with CDES01 and CDES04 indicate that both messages accumulate in a seed-specific manner with a peak at 21 days after anthesis. However, expression patterns also indicate that regulation between CDES01 and CDES04 are slightly different. The CDES01 message accumulates at a low level in young leaves in addition to seeds, whereas accumulation of the RNA transcript corresponding to CDES04 is restricted to seeds. This observation implies the presence of at least two isozymes of SACPD having overlapping but slightly distinct functions in sesame.

The immature sugar cane stalks studied contained less than 7% sucrose, and showed the activities of enzymes such as invertase, alpha-galactosidase, alpha-mannosidase, beta-N-acetylglucosaminidase, beta-glucosidase, beta-xylosidase, and beta-galactosidase. The alpha-galactosidase was highly purified by ammonium sulfate fractionation, gel filtration on a Sephadex G-100 column, ionexchange chromatography on DEAE-cellulose, and CM-cellulose columns, and heat treatment (60 degrees C, 15 min) in the presence of 0.2 m D-galactose. In polyacrylamide gel electrophoresis, the purified enzyme was homogeneous, having a molecular weight of approximately 46,000. In gelfiltration, it was approximately 47,000. The activity was optimum at pH 4.5 and at 60 degrees C. The purified enzyme hydrolyzed p-nitrophenyl-alpha-D-galactopyranoside (Km, 0.83 mM; Vmax, 25.0 mumol/mg/min), raffinose (Km, 25.9 mM; Vmax, 15.4 mumol/mg/min), and stachyose (Km, 13.0 mM; Vmax 2.7 mumol/mg/min), in addition to melibiose, guar gum, and locust bean gum. The hydrolysis of p-nitrophenyl-alpha-D-galactopyranoside was markedly inhibited by HgCl2, AgNO3, p-chloromercuribenzoate (PCMB), L-ascorbic acid, melibiose, stachyose, and D-galactose. Also the purified enzyme showed a lectin activity with trypsinized erythrocytes.

The chemical and catalytic properties of potato phosphoglucomutase [EC 2.7.5.1] were studied using various enzyme species (Peaks Ia, Ib, Ic, and II; Takamiya, S. & Fukui, T. (1978) Plant Cell Physiol. 19, 319--328). The molecular weights of the species are all approximately 60,000. No indication of the presence of subunit structure was obtained under various conditions. The amino acid composition of Peak Ia is generally similar to those of the enzymes from other sources, though it has some peculiarities. The Peak Ia and Peak II enzymes both absolutely require alpha-D-glucose 1,6-bisphosphate and Mg2+ for activity, and appear to have a "ping-pong" mechanism. A low concentration of Be2+ inhibits their action, the inhibition being retarded either by Mg2 or EDTA. Although the inhibition patterns by various metabolites, are similar for Peaks Ia and II, they differ in their kinetic parameters and optimal pH values.