Abstract
The peroxisomal enzyme dihydroxyacetone phosphate (DHAP) acyltransferase shows a differential response to acetaldehyde. Employing whole peroxisomes, the enzyme displays a 130-400% stimulation of activity when assayed in the presence of 10-250 mM acetaldehyde. Following taurocholate solubilization of the enzyme the response to 0.25 M acetaldehyde is one of almost total inhibition. This inhibition of the taurocholate-solubilized enzyme is not observed at acetaldehyde concentrations below 200 mM. The stimulation of DHAP acyltransferase by acetaldehyde is solely a response of the peroxisomal enzyme as evidenced by its insensitivity to N-ethylmaleimide and 5 mM glycerol 3-phosphate. Furthermore, microsomal dihydroxyacetone phosphate acyltransferase activity is inhibited at all acetaldehyde concentrations. The activation of membrane-bound DHAP acyltransferase by acetaldehyde appears to be specific for this enzyme in comparison to several other peroxisomal and microsomal enzymes. The specificity of activation and differential response of the peroxisomal enzyme to acetaldehyde indicates that the microenvironment of the peroxisomal membrane is important for normal enzymatic function of this enzyme.
Highlights
From the Department of Anatomy, Physiological Scienceasnd Radiology and the Department of Biochemistry, North Carolina State University School of Veterinary Medicine, Raleigh,North Carolina 27606
An increase of20-45% over the control activity is observed when peroxisomes areincubated with 10 mM N ethylmaleimide (NEM) andenzyme activity measured at pH 7.4 [2, 10]
Data presented in this paper describe a specific 3-4-fold stimulation of membrane-bound peroxisomal dihydroxyacetone phosphate (DHAP) acyltransferase activity measured at pH7.4 by the ethanol metabolite acetaldehyde
Summary
The peroxisomal enzyme dihydroxyacetone phosphate (DHAP) acyltransferase showsa differential response to acetaldehyde. The stimulation of DHAP acyltransferase by acetaldehyde is solely a response of the peroxisomal enzyme as evidenced by its insensitivity to N-ethylmaleimide and 5 mM glycerol 3-phosphate. The activation of membrane-bound DHAP acyltransferase by acetaldehyde appears to be specific for this enzyme in comparison to several other peroxisomal and microsomal enzymes. Peroxisomal DHAP acyltransferase has been shown to be stimulated by some of the known inhibitors of the microsomal enzyme. Use of the detergent taurocholate serves to solubilize a major portion of peroxisomal DHAP acyltransferase activity from the membrane, resulting in a 3-4-fold increase in activity. Data presented in this paper describe a specific 3-4-fold stimulation of membrane-bound peroxisomal DHAP acyltransferase activity measured at pH7.4 by the ethanol metabolite acetaldehyde. The differential response of the peroxisomal enzyme to acetaldehyde is discussed in relation to the role of the lipoprotein microenvironment surrounding the enzyme
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
