Question

SDS-Page Questions : Please answer all questions & explain.

1.Can I use SDS- page to diagnosis the urea cycle disorder : Arginase deficiency?

2.Would the mutated arginase have a different MW compared to the normal arginase?

3.Could you recognize/detect the mutated arginase on SDS- Page?

Answer 1

Thank you for your question:

1) SDS-PAGEA could be partially used for identifying arginase deficiency in cases where the arginase is completely missing or in cases where it is it's expression is incomplete ( low Milner ; non- functional protein). However, in majority of the cases, Arginase is partially expressed i.e. the protein is there, however, it's expression is less than a normal individual. In those cases, SDS-PAGE won't be able to diagnose arginase deficiency (since arginase could be expressed less depending on diet/ environmental factors in normal individuals as well).

(2) Continued from Answer (1), in some individuals with incomplete expression of arginase, mutated arginase might have low mol weight than normal arginase. However, in majority of cases, phenotypic expression of arginase is not mutated, however, the gene is mutated leading to partial expression of arginase.

(3) In most cases, one cannot detect the mutated arginase on SDS-PAGE except where there is incomplete expression of arginase where mutated arginase might have low mol weight than normal arginase and would be identified in SDS page. However, having said that, without the genetic identification of SDS-PAGE fragment, identification of mutated arginase just from SDS-PAGE won't be possible since there would be many other proteins that would be identified in plasma.