Enzymes are biological molecules, usually proteins, that are responsible for thousands of metabolic processes in the body. Metabolic processes are the organic functions that are required in a cell or organism to sustain life. Almost all chemical reactions/metabolic processes in a biological cell need enzymes to occur.
Succinate dehydrogenase is an enzyme found in the mitochondria (the part of the cell responsible for cellular respiration). It functions not only in mitochondrial cell respiration and energy generation, but also plays a role in oxygen level sensing and tumor suppression. This enzyme is comprised of four subunits: Subunit A, Subunit B, Subunit C and Subunit D.
To further break it down, succinate dehydrogenase is an enzyme made of amino acids. All biological proteins (including enzymes) are made of sequences of amino acids. The information supplied to the cells about how to make the enzyme is supplied by the DNA. The DNA provides the genetic template for all the biomolecules that make up our body; eye color, hair color, bones, blood type, etc. Similarly, when succinate dehydrogenase is made in the body, DNA provides the genetic code/template for the type and sequence of amino acids in the enzyme.
When there is a defect (i.e. mutation) in the genetic code, an incorrect amino acid may be used in the enzyme. This sometimes can change the shape and function of the enzyme.
When succinate dehydrogenase isn’t functioning properly, it can send out signals of low-oxygen (ie; pseudohypoxia) and may stop inhibiting tumour growth. The effect of this malfunction can be seen in the tumour growth we see associated with the SDHx mutations.
References: Eng, C., Kiurus, M., Magali, F.J., & Aaltonen, L. A. (2003) A role for mitochondrial enzymes in inherited neoplasia and beyond. Nature Reviews: Cancer, 3, 193-2003.
Retrieved on January 16, 2014 from http://ww2.biol.sc.edu/~bergerlab/599%20PAPERS/pdfs/Mito%20and%20Cancer.pdf