Question: As we were looking through lab exercise and discussing it during class, I saw that we would be working with the LDH gene. I had heard of the LDH protein in my previous biochemistry classes, but as to what function it had in the body, I did not really know. My question would be what is LDH, what does it do, and what relevance does it have in the medical world?
Answer: LDH, or lactate dehydrogenase is an enzyme that catalyzes the conversion of pyruvate to lactate and vice versa by using NADH and NAD+ to donate and accept protons. Proton acceptance from NADH is usually performed by oxygen, turning oxygen into water. In the absence of oxygen, this role is filled by pyruvate. LDH is found in all the domains of life in almost all living cells. In humans, LDH is a protein that is not supposed to appear in the blood at high levels, and levels are often measured in the doctor’s office to detect and monitor health abnormalities. Since LDH is released into the blood when cells have been damaged or destroyed, high levels of LDH indicate that there has been tissue damage somewhere in the body. It is used to test for a broad range of illnesses, including “cancer, heart failure, hypothyroidism, anemia, pre-eclampsia, meningitis, encephalitis, acute pancreatitis, HIV, and lung or liver disease.”
LDH is often associated with contributing to muscular fatigue due to in its production of lactate during exercise., However, but experiments have shown that although LDH seems to be connected with muscle fatigue, it does not cause it. Interestingly, it actually helps prevent muscular acidosis and delays the fatigue that is caused by those unaccepted NADH protons by transferring them to pyruvate. This allows the pyruvate to lactate reaction to act as a kind of buffer, keeping the protons from accumulating and causing the muscular acidosis and fatigue.
- Natalya R.
References:
- https://labtestsonline.org/understanding/analytes/ldh/tab/test/
- https://en.wikipedia.org/wiki/Lactate_dehydrogenase
- Stanford Cancer Center. “Cancer Diagnosis – Understanding Cancer”. Understanding Cancer. Stanford Medicine.
Biochemistry Q&A Blog 
Very insightful article especially since one goal of this lab is to isolate this enzyme.
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Very interesting BQA! I really enjoyed reading your answer because it applies what we’re learning in class as to how LDH is relevant in both the biochemistry and medical world. I did not know that the presence of the LDH enzyme may be an indicator of tissue damage and I can see why we chose to isolate this enzyme and it seems that further research on LDH is promising!
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Recent research on LDH has shown that LDH5 can be used as an anticancer drug target, since it’s upregulated in tumors, and might even help reverse the cancer resistance to traditional chemo- and radiation therapy. Here’s the link, if you’re interested in taking a look at the background on how it can be used: http://www.ncbi.nlm.nih.gov/pubmed/25528630
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This is an interesting article. Good Job! Just wants to add a bit more information on LDH and its role in cancer. Most cancers have increased LDH activity and decreased Kreb’s or TCA cycle. This phenomenon was first observed and discovered by Otto Warburg and hence, referred as “Warburg effect” or “aerobic glycolysis” The beneficial effects of higher lactate or acidosis is still not clear but inhibiting LDH activity or reversing the flux into Kreb’s cycle prevents tumor growth and metastasis.
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Weird, that I cannot see my posted comments! I hope you all can see them though. Thanks!
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Thanks Su K. In class we talked about LDH in normal physiology, but did not get into its involvement in tumor physiology. This insight into LDH’s role in cancer biology is very interesting.
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