LDH Isoenzymes - Lab Report for LDH PDF

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Lab Report for LDH...

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Friedman 1 Robby Friedman BIL 256 Dr. DiResta March 28th, 2019 LDH Isoenzymes The enzyme LDH (lactate dehydrogenase) is a tetramer made up of a combination of two different monomers, H monomer and M monomer. The H monomer is preferentially expressed in cardiac cells, whereas the M monomer is expressed in skeletal muscle cells. Since LDH is a combination of different monomers, it is expected to get differences between LDH 1, 2, 3, 4, and 5. The H monomer has more acidic amino acids than the M monomer, resulting in a greater negative charge and faster rate of movement. The M monomer has a higher affinity for the substrate, pyruvate, than the H monomer causing it to convert more lactate efficiently. The purpose of this experiment is to observe and identify the LDH isoenzymes. This was performed using tissue extracts from calf thymus, heart, skeletal muscle, and serum. The extracts were then electrophoresed on agarose gel, and stained. We observed the tissue profiles and determined the heart cells to contain LDH 1, 2, and 3, whereas skeletal muscle cells contained mostly LDH 4 and LDH 5. This is expected as the heart should contain more H monomers than M monomers, to prevent a build-up of lactic acid, which can cause muscle fatigue. Since LDH 4 and 5 convert pyruvate to lactate more efficiently, it makes sense to see more LDH 4 and 5 in skeletal muscle tissue. To conclude, the H monomer is more present in cardiac cells as displayed in the experiment, as there are more LDH 1, 2, and 3 bands present, whereas there are more M monomers present in skeletal muscle, shown by the LDH 4 and 5 bands....