Creatine-creatine phosphate shuttle modeled as two-compartment system at different levels of creatine kinase activity.
نویسنده
چکیده
In order to characterize ADP-ATP and creatine-creatine phosphate (Cr-CrP) shuttles a minimal mathematical model with two compartments and cyclic turnover of matter was designed. The 'mitochondrial' compartment contained 'ATP-synthase' and 'mitochondrial creatine kinase' (mitCK). The 'cytoplasmic' compartment consisted of 'ATPase', 'cytoplasmic creatine kinase' (cytCK) and an 'ADP-binding structure'. The exchange of metabolites between these compartments was limited. Different levels of cytCK and mitCK expression as well as different exchange rate constants between the compartments were assigned to obtain several different modes. Every steady state obtained in the presence of low ATPase activity ('resting' conditions) was then disturbed by a steep activation of ATPase ('muscle performance') and afterwards the transition to a new steady state was followed in time. The ATP-buffering capacity of the system initially acquired by cytCK expression significantly increased after additional mitCK supplement. Nevertheless, even the complete Cr-CrP shuttle failed to maintain a high [ATP]/[ADP] ratio during long term 'muscle performance' due to the rate limiting CK-transphosphorylation in the mitochondria. The facilitated diffusion of Cr and CrP was not critical, and the model worked with the same efficiency even at equal permeabilities for nucleotides and guanidines. Under 'resting conditions' the main flux of matter went through the Cr-CrP shuttle, resulting in 'pumping' of CrP. This ensured a 40 s delay in the [ATP] decrease at 'work'. The partial systems without mitCK were not as effective, and this delay was 0-10 s. However, the ADP-ATP shuttle was of more importance at the steady state achieved under 'working' conditions.
منابع مشابه
In Vitro Inhibition of Human Sperm Creatine Kinase by Nicotine, Cotinine and Cadmium, as a Mechanism in Smoker Men Infertility
Background Nicotine, cotinine and cadmium are harmful components of cigarettes that have an effect on human reproductive function. Although the effects of cigarette smoke on male reproductive function is characterized in several articles its mechanism of action is still unknown. In the present study, we investigate the effect of nicotine, cotinine and cadmium on human sperm creatine kinase acti...
متن کاملThe Effect of Cigarette Smoking on Human Sperm Creatine Kinase Activity: As An ATP Buffering System in Sperm
متن کامل
In vitro Effect of Lead, Silver, Tin, Mercury, Indium and Bismuth on Human Sperm Creatine Kinase Activity: a Presumable Mechanism for Men Infertility
Background: The aim of the present study was to investigate the in vitro effects of mercury (Hg+2), lead (Pb+2), silver (Ag+2), tin (Sn+2), bismuth (Bi+3) and indium (In+3) ions on sperm creatine kinase. Methods: creatine kinase was isolated from human sperm homogenates after chromatography on a DEAE cellulose column. Results: At 60 µg ml-1 metal concentration, 70% of the creatine kinase activi...
متن کاملCreatine Kinase of Rat Heart Mitochondria COUPLING OF CREATINE PHOSPHORYLATION TO ELECTRON TRANSPORT*
Intact mitochondria from human, beef, and rat heart, as well as rat brain and rat skeletal and smooth muscle, contain considerable creatine kinase activity; those from rat or rabbit liver, kidney, and testis contain essentially none. In rat heart mitochondria creatine kinase activity is far higher than the activity of adenylate kinase and nucleoside diphosphokinase. The heart mitochondrial crea...
متن کاملNOVEL REAGENTS FOR CREATINE KINASE
The purpose of this investigation was to develop a simple colorimetric method for creatine kinase (CK). The new method is based on the reaction of creatine, formed enzymatically from creatine phosphate and ADP, with different glyoxal compounds. Hydrated glyoxals, such as para-nitrophenyl, 2-thiophene, 4- biphenyl, 4, 4' -biphenyl,α-naphthyl, β-naphthyl, para-chlorophenyl, and styryl were...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
- Biochimica et biophysica acta
دوره 1208 2 شماره
صفحات -
تاریخ انتشار 1994