scholarly journals Glucose metabolism in the mucosa of the small intestine. A study of hexokinase activity

1968 ◽  
Vol 109 (1) ◽  
pp. 35-42 ◽  
Author(s):  
L M Srivastava ◽  
P. Shakespeare ◽  
G. Hübscher
Keyword(s):  
Small Intestine ◽  
Lactate Dehydrogenase ◽  
Glucose Metabolism ◽  
Guinea Pig ◽  
Intestinal Mucosa ◽  
Brush Border ◽  
Deae Cellulose ◽  
Mitochondrial Fraction ◽  
Type Ii ◽  
Hexokinase Activity

1. The intracellular distribution of hexokinase activity was studied in the mucosa of rat and guinea-pig small intestine. In the rat 60% and in the guinea pig 45% of the hexokinase activity of homogenates were recovered in a total particulate fraction that contained only 5–17% of the homogenate activity of hexose phosphate isomerase, pyruvate kinase, lactate dehydrogenase and overall glycolysis (formation of lactate from glucose). 2. Fractionation of homogenates from guineapig small intestine showed that the particulate hexokinase activity was chiefly in the mitochondrial fraction with a small proportion in the nuclei plus brush-border fraction. 3. After chromatography of the particle-free supernatants on DEAE-cellulose, hexokinase types I and II were determined quantitatively. No evidence was obtained for the presence of hexokinase type III or glucokinase. In the preparations from guinea pigs, hexokinase types I and II amounted to 69% and 31% respectively of the eluted activity; the corresponding values for preparations from rats were 5·8% and 94·2%. 4. Total and specific hexokinase activities decreased significantly in homogenates and particle-free supernatants prepared from the intestinal mucosa of rats starved for 36hr. and increased again after re-feeding. The decrease in hexokinase activity in the particle-free supernatant from starved rats was chiefly due to a decrease in the type II enzyme.

scholarly journals Purification of phosphodiesterase II from rat and guinea-pig intestinal mucosa

1976 ◽  
Vol 155 (3) ◽  
pp. 607-613 ◽  
Author(s):  
P R Flanagan ◽  
S H Zbarsky
Keyword(s):  
Guinea Pig ◽  
Intestinal Mucosa ◽  
Deae Cellulose ◽  
Large Loss ◽  
Arrhenius Plots ◽  
The Poor ◽  
Km Value ◽  
Soluble Material

Phosphodiesterase II from extracts of intestinal mucosa of rat and guinea pig was purified by chromatography on DEAE-cellulose, CM-cellulose and agarose. The rat enzyme was purified 350-550-fold, with recoveries ranging up to 46%. The best purification of the guinea-pig enzyme was 15-fold, and the recovery was only 2.6%, the large loss occurring during chromatography on DEAE-cellulose and agarose. The poor results with the guinea-pig enzyme reflect the difficulty in obtaining a truly soluble material. Repeated sonication of the crude guinea-pig preparations yielded material that was initially soluble but tended to re-aggregate quickly. Purification of the rat phosphodiesterase II increased its thermostability, the temperature of half-inactivation being increased from 54degrees to 60degreesC. Both enzymes had a Km value of 4 × 10(-5) M with thymidine 3′-(2,4-dinitrophenyl) phosphate as substrate and showed similar pH optima for activity. Both enzymes were inhibited slightly in 0.1 M-MgC12 or 2M-urea and much more strongly in 2M-(NH4)2SO4 or 6M-NaC1. The guinea-pig enzyme was usually inhibited more than the rat enzyme. The Arrhenius plots of the two enzymes differed slightly in slope, but both were biphasic, showing breaks between 30degrees and 40degreesC. It was concluded that the two enzymes were markedly similar in behaviour and that the differences found were related to the different degrees of purification attained by the procedures described.

scholarly journals Similarities between a dipeptide hydrolase from brush-border and cytosol fractions of guinea-pig intestinal mucosa

1976 ◽  
Vol 159 (3) ◽  
pp. 715-717 ◽  
Author(s):  
C O Piggott ◽  
G O'Cuinn ◽  
P F Fottrell
Keyword(s):  
Guinea Pig ◽  
Intestinal Mucosa ◽  
Brush Border ◽  
Cytosol Fraction ◽  
Brush Border Membranes ◽  
Peptide Hydrolase

A dipeptide hydrolase from the brush border of guinea-pig intestinal mucosa was purified. The enzyme resembles another dipeptide hydrolase isolated from the cytosol fraction of intestinal mucosa. Studies on the binding of cytosol peptide hydrolase to brush-border membranes indicate that the enzyme found in the brush border may be a cytoplasmic contaminant.

Stimulation of protein absorption in the newborn piglet's intestine through the use of polyvalent cations

1972 ◽  
Vol 15 (2) ◽  
pp. 139-146 ◽  
Author(s):  
M. W. Smith ◽  
K. A. Burton
Keyword(s):  
Small Intestine ◽  
Intestinal Mucosa ◽  
Brush Border ◽  
Protein Transport ◽  
Brush Border Membrane ◽  
Direct Action ◽  
Plasma Albumin ◽  
Bovine Plasma ◽  
Stimulation Of

SUMMARYThe transport of protein across the small intestine of the newborn pig was measured in vitro. The transport of both bovine immune globulin and bovine plasma albumin showed a large variation between piglets. The polycations poly-ornithine, poly-arginine and poly-lysine stimulated both the transport of globulin and albumin. Protamine, histone and arginine were without effect on protein transport. Poly-ornithine became bound to albumin and to the piglet intestinal mucosa. The amount of poly-ornithine needed to stimulate albumin transport was of the same order as that needed to change the electrophoretic mobility of brush border membranes and some 30 times less than that needed to change the charge on the protein. It is concluded that polycations stimulate protein transport by a direct action on the brush border membrane of the pig intestinal mucosa.

scholarly journals Mammalian small intestinal phytase (EC 3.1.3.8)

1983 ◽  
Vol 50 (3) ◽  
pp. 673-678 ◽  
Author(s):  
John R. Cooper ◽  
Helen S. Gowing
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Metal Ions ◽  
Brush Border ◽  
Small Intestinal ◽  
Competing Reactions

1. Phytase (EC 3.1.3.8) concentration has been measured in the small intestineof rat, rabbit, guinea-pig and hamster. Levels varied from 0·12 units (μg phosphorus released/min)/mg protein in the rat to 0·03 units/mg protein in the rabbit.2. The enzyme is localized in the brush border of the small intestine of the rat.3. It is suggested that the levels and location of phytase are an important factor inthe uptake of metals from metal–phytate complexes. Metal ions released in the immediate vicinity of the absorptive surface of the intestine could be absorbed before being rendered insoluble by competing reactions such as hydrolysis.

scholarly journals Glucose metabolism in the rat small intestine: the effect of glucose analogues on hexokinase activity (Short Communication)

1973 ◽  
Vol 132 (1) ◽  
pp. 125-128 ◽  
Author(s):  
Gwyneth M. Jones ◽  
R. John Mayer
Keyword(s):  
Small Intestine ◽  
Glucose Metabolism ◽  
Short Communication ◽  
Subcellular Location ◽  
Rat Small Intestine ◽  
Hexokinase Activity ◽  
A Value ◽  
Glucose Analogues ◽  
Effect Of Glucose

The effect of intubation of starved rats with solutions of glucose, 3-O-methylglucose, mannose, 2-deoxyglucose and sorbitol on the subcellular location of hexokinase in the mucosa of the small intestine was studied. Glucose, 3-O-methylglucose and mannose caused the soluble hexokinase activity to rise to a value similar to that found in fed animals, whereas sorbitol and 2-deoxyglucose caused smaller increases.

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