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P C Simons

Publications and source records attributed to P C Simons.

7 recordsLinked to original sources
PubMed1990

Improvement of phosphorus availability by microbial phytase in broilers and pigs.

Techniques have been developed to produce microbial phytase for addition to diets for simple-stomached animals, with the aim to improve phosphorus availability from phytate-P in plant sources. The activity of the crude microbial phytase showed pH optima at pH 5.5 and 2.5. The enzyme was able to degrade phytate in vitro in soya-bean meal, maize and a liquid compound feed for pigs. When microbial phytase was added to low-P diets for broilers the availability of P increased to over 60% and the amount of P in the droppings decreased by 50%. The growth rate and feed conversion ratio on the low-P diets containing microbial phytase were comparable to or even better than those obtained on control diets. Addition of microbial phytase to diets for growing pigs increased the apparent absorbability of P by 24%. The amount of P in the faeces was 35% lower.

6-Phytase↗
PubMed1989

cDNA cloning and predicted amino acid sequence of Glycera dibranchiata monomer hemoglobin IV.

The three major monomer hemoglobins from Glycera dibranchiata erythrocytes isolated in this laboratory were sequenced from their N-termini. A stretch of amino acid sequence identity was used to determine the sequence of a mixed oligodeoxynucleotide that would be complementary to all 12 possible mRNA sequences coding for the amino acids. A cDNA library was constructed by using poly(A+) RNA from G. dibranchiata erythrocytes, the library was probed with the oligonucleotide, and the longest positive inserts found were subcloned into a sequencing plasmid and then sequenced. The first one was 745 bases long, containing 85 bases of 5'-untranslated RNA, an open reading frame of 444 bases coding for 148 amino acids, and a 3'-untranslated region of 216 bases. The predicted amino acid sequence matches the first 25 amino acids of G. dibranchiata monomer globin component IV. The sequence contains an N-terminal methionine plus 18 other mostly conservative sequence changes compared to the published sequence of Imamura et al. (1972), which appears from our partial sequencing to be monomer globin component II. We confirm the presence of leucine in the E7 position, which is histidine in most myoglobins and hemoglobins.

Amino Acid Sequence↗
PubMed1989

A stopped-flow mixer device for a batch microcalorimeter application to NAD-NADase reaction.

A new molded polypropylene, diamond-like carbon (DLC)-coated mixing cell has been developed for use in the batch microcalorimeter. Reagent volume can be varied from 25 microliters to 100 microliters. A 10 microcalorie reaction heat can be measured to 5%. Repeat reactions can be done as often as every 10 min for a fast reaction. Reactions can be started within 1 h or less after loading. A pre-equilibrator and a temperature-controlled syringe drive unit permit solutions to be stored at 4 degrees C while being run at any temperature from -20 degrees C to 40 degrees C. The kinetics and enthalpy of reaction of NAD-NADase have been measured. delta H is about 21 kcal/mol endothermic.

Calorimetry↗
PubMed1988

Site-directed mutagenesis of yeast cytochrome c peroxidase shows histidine 181 is not required for oxidation of ferrocytochrome c.

The long-distance electron transfer observed in the complex formed between ferrocytochrome c and compound I, the peroxide-oxidized form of cytochrome c peroxidase (CCP), has been proposed to occur through the participation of His 181 of CCP and Phe 87 of yeast iso-1 cytochrome c [Poulos, T. L., & Kraut, J. (1980) J. Biol. Chem. 255, 10322-10330]. We have examined the role of His 181 of CCP in this process through characterization of a mutant CCP in which His 181 has been replaced by glycine through site-directed mutagenesis. Data from single-crystal X-ray diffraction studies, as well as the visible spectra of the mutant CCP and its 2-equiv oxidation product, compound I, show that at pH 6.0 the protein is not dramatically altered by the His 181----Gly mutation. The rate of peroxide-dependent oxidation of ferrocytochrome c by the mutant CCP is reduced only 2-fold relative to that of the parental CCP, under steady-state conditions. Transient kinetic measurements of the intracomplex electron transfer rate from ferrous cytochrome c to compound I indicate that the rate of electron transfer within the transiently formed complex at high ionic strength (mu = 114 mM, pH = 6) is also reduced by approximately 2-fold in the mutant CCP protein. The relatively minor effect of the loss of the imidazole side chain at position 181 on the kinetics of electron transfer in the CCP-cytochrome c complex precludes an obligatory participation of His 181 in electron transfer from ferrous cytochrome c to compound I.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytochrome c Group↗
PubMed1978

Twisted legs in broilers.

The effect of various factors on the incidence of leg abnormalities, with particular reference to twisted leg, in broilers was studied. The incidence of twisted legs was influenced by strain and for males was twice that for females. There was also a higher incidence in cages than on litter with the type of cage floor having an effect: broilers reared on floors of metal wire and perforated sheets had more leg problems than those reared on plastic mats and plastic-covered wire. Although vitamin and mineral supplementation had no effect on caged broilers, a restriction of metabolisable energy (ME) intake during the first 14 d after hatching halved the frequency of leg abnormalities compared with those fed ad libitum. Studies of cage size and location of water suggested that a lack of exercise increases the incidence of leg abnormalities.

Animals↗