Effects of Phospholipase A and Triton X-100 on Guanylate Cyclase Activity in Mammary Gland Homogenates from Mice

1978 ◽  
Vol 10 (04) ◽  
pp. 331-336 ◽  
Author(s):  
J. Rillema ◽  
B. Linebaugh
Keyword(s):  
Mammary Gland ◽  
Guanylate Cyclase ◽  
Phospholipase A ◽  
Cyclase Activity ◽  
Guanylate Cyclase Activity ◽  
Triton X

scholarly journals The metabolism of cyclic nucleotides in the guinea-pig pancreas. Adenylate cyclase and guanylate cyclase

1980 ◽  
Vol 186 (2) ◽  
pp. 499-505 ◽  
Author(s):  
M Lemon ◽  
P Methven ◽  
K Bhoola
Keyword(s):  
Adenylate Cyclase ◽  
Guinea Pig ◽  
Guanylate Cyclase ◽  
Cyclic Nucleotides ◽  
Cyclase Activity ◽  
Dependent Manner ◽  
Guanylate Cyclase Activity ◽  
Triton X ◽  
Dose Dependent ◽  
Significant Activation

Adenylate cyclase from the guinea-pig pancreas was activated in a dose-dependent manner by both secretin and cholecystokinin-pancreozymin, but in contrast with results in other species the hormones were approximately equipotent. All other hormones and transmitter substances tested were without any effect on adenylate cyclase activity. Guanylate cyclase activity was shown to have both particulate and supernatant components in the guinea-pig pancreas. The particulate enzyme, but not the supernatant enzyme, was markedly activated by Triton X-100, and most of the induced activity was released into the supernatant. The supernatant enzyme was specifically Mn2+-dependent, but, even though Mn2+ was maximally effective at a concentration of 3 mM, activity could be raised further by increasing Ca2+ concentration. The particulate enzyme, by contrast, was relatively Mn2+-independent. Activity of the particulate guanylate cyclase was enhanced by phosphatidylserine. The supernatant enzyme displayed classical Michaelis-Menten kinetics, but the particulate enzyme deviated markedly from such kinetics. Under none of the conditions used was any significant activation of guanylate cyclase observed with any of the secretogen hormones or transmitter substances.

scholarly journals Factors affecting the activity of guanylate cyclase in lysates of human blood platelets

1978 ◽  
Vol 174 (1) ◽  
pp. 23-35 ◽  
Author(s):  
A F Adams ◽  
R J Haslam
Keyword(s):  
Guanylate Cyclase ◽  
Cyclic Gmp ◽  
Specific Activity ◽  
Adenine Nucleotides ◽  
Blood Platelets ◽  
Cyclase Activity ◽  
Temperature Dependent ◽  
Factors Affecting ◽  
Guanylate Cyclase Activity ◽  
Triton X

1. Under optimal ionic conditions (4 mM-MnCl2) the specific activity of guanylate cyclase in fresh platelet lysates was about 10nmol of cyclic GMP formed/20 min per mg of protein at 30 degrees C. Activity was 15% of optimum with 10mM-MgCl2 and negligible with 4mM-CaCl2. Synergism between MnCl2 and MgCl2 or CaCl2 was observed when [MnCl2] less than or equal to [GPT]. 2. Lower than optimal specific activities were obtained in assays containing large volumes of platelet lysate, owing to the presence of inhibitory factors that could be removed by ultrafiltration. Adenine nucleotides accounted for less than 50% of the inhibitory activity. 3. Preincubation of lysate for 1 h at 30 degrees C increased the specific activity of platelet guanylate cyclase by about 2-fold. 4. Lubrol PX (1%, w/v) stimulated guanylate cyclase activity by 3–5-fold before preincubation and by about 2-fold after preincubation. Triton X-100 was much less effective. 5. Dithiothreitol inhibited the guanylate cyclase activity of untreated, preincubated and Lubrol PX-treated lysates and prevented activation by preincubation provided that it was added beforehand. 6. Oleate stimulated guanylate cyclase activity 3–4-fold and arachidonate 2–3-fold, whereas palmitate was almost inactive. Pretreatment of lysate with indomethacin did not inhibit this effect of arachidonate. Oleate and arachidonate caused marked stimulation of guanylate cyclase in preincubated lysate, but inhibited the enzyme in Lubrol PX-treated lysate. 7. NaN3 (10mM) increased guanylate cyclase activity by up to 7-fold; this effect was both time- and temperature-dependent. NaN3 did not further activate the enzyme in Lubrol PX-treated lysate. 8. The results indicated that preincubation, Lubrol PX, fatty acids and NaN3 activated platelet guanylate cyclase by different mechanisms. 9. Platelet particulate fractions contained no guanylate cyclase activity detectable in the presence or absence of Lubrol PX that could not be accounted for by contaminating soluble enzyme, suggesting that physiological aggregating agents may increase cyclic GMP in intact platelets through the effects of intermediary factors. The activated and inhibited states of the enzyme described in the present paper may be relevant to the actions of these factors.

Guanylate Cyclase Activity in Normal and Neoplastic Squamous Epithelia from the Upper Aero-Digestive Tract

ORL ◽  
1986 ◽  
Vol 48 (5) ◽  
pp. 265-269
Author(s):  
E.L. Rydell ◽  
K.L. Axelsson ◽  
J. Olofsson ◽  
J.E.S. Wikberg
Keyword(s):  
Digestive Tract ◽  
Guanylate Cyclase ◽  
Cyclase Activity ◽  
Guanylate Cyclase Activity ◽  
Squamous Epithelia

scholarly journals Identification of a novel Arabidopsis thaliana nitric oxide-binding molecule with guanylate cyclase activity in vitro

FEBS Letters ◽  
2011 ◽  
Vol 585 (17) ◽  
pp. 2693-2697 ◽  
Author(s):  
Takalani Mulaudzi ◽  
Ndiko Ludidi ◽  
Oziniel Ruzvidzo ◽  
Monique Morse ◽  
Nicolette Hendricks ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Arabidopsis Thaliana ◽  
Guanylate Cyclase ◽  
Cyclase Activity ◽  
Guanylate Cyclase Activity

scholarly journals Histochemistry of guanylate cyclase activity.

1995 ◽  
Vol 43 (12) ◽  
pp. 1235-1240 ◽  
Author(s):  
S Mehdizadeh ◽  
A O'Farrell ◽  
L Bitensky ◽  
J Weisz ◽  
J Alaghband-Zadeh ◽  
...  
Keyword(s):  
Guanylate Cyclase ◽  
Cyclase Activity ◽  
Lead Ions ◽  
Ammonium Citrate ◽  
Considerable Proportion ◽  
Guanosine Triphosphate ◽  
Guanylate Cyclase Activity ◽  
Metal Capture ◽  
Cryostat Sections ◽  
Sufficient Concentration

Guanylate cyclase liberates pyrophosphate from guanosine triphosphate (GTP). In studies published previously, this phosphate is trapped by lead ions even though it is known that free lead ions inactivate a considerable proportion of this enzymatic activity. To overcome the damaging effects of fixation, this study used fresh cryostat sections stabilized with a sufficient concentration of a collagen-derived polypeptide to ensure no measurable loss of guanylate cyclase activity. To avoid the damaging influence of free lead ions, we used a hidden metal capture reagent, i.e., a complex of lead ammonium citrate/acetate that does not react with GTP but which rapidly forms a precipitate with the pyrophosphate liberated by the enzyme. The lead precipitate is then converted into the colored sulfide which is measured in individual cells by microdensitometry. This system was used to measure guanylate cyclase activity in individual cells in unfixed sections of rat liver.

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