Question

12. What is the activity of phosphatases, how do acid and alkaline phosphatase differ, and what are some possible causes of abnormal levels?

13. What is the activity of lactate dehydrogenase, and what might cause plasma levels to be abnormally elevated?

14. Given the abnormally elevated levels of both alkaline phosphatase and lactate dehydrogenase, is there one particular organ that is likely affected? Explain.

Answer 1

12. Phosphatases or phosphomonoesterases are the hydrolytic enzymes, that uses water to cleave a phosphoric acid monoester into a phosphate ion and an alcohol thus  removing a phosphate moiety from the substrate.

Major difference between acid phosphatase and alkaline phosphatase i the pH range at which their activity is optimum. Acid phosphatases are mostly active between pH 4.5 - 6.0 while alkaline phosphatases are active optimally between pH 9 - 11

Abnormal levels of phosphatase occurs in condition like, Paget's disease,(a chronic disease of the skeleton) hyperparathyroidism, osteomalacia, metastatic bone disease etc. .Even if fracture occurs, the levels of phosphatase are usually high.

13 Lactate dehydrogenase is a tetrameric enzyme that catalyzes the conversion of lactate to pyruvate and back, and also in inter conversion of nicotinamide adenine dinucleotide (NAD)H to NAD

Conditions that can cause increased LDH in the blood include liver disease, heart attack, anemia, muscle trauma, bone fractures, cancers, and infections such as meningitis, HIV.

14. One particular organ would be liver, whenever liver cells are damaged or injured, these enzymes leak out into the circulation across the damaged cell membrane. In a disease like Visceral leishmaniasis (VL), also known as kala-azar, which is parasitic disease that affects organs like liver and spleen, these enzymee levels were elevated.