In connection with the tryptophan operon, that an excess of tryptophan can cause a repression of the genes of this operon, leading to an arrest of the synthesis of the enzymes required for the formation of tryptophan. Beside this possibility of repression, there is very often feedback inhibition, i.e. the possibility for an essential metabolite (amino acid, nucleotide, etc.), which [...]
In this article we will discuss about the tests for estimation of acid phosphatase in plants. Principle: The enzyme phosphatase hydrolyzes p-nitro-phenol phosphate. The released p-nitro-phenol is yellow in colour in alkaline medium and is measured at 405 nm. The optimum pH for acid and alkaline phosÂphatases are 5.3 and 10.5, respectively. Materials: (i) Sodium Hydroxide 0.085 N: Dissolve 0.85 [...]
In this article we will discuss about the tests for estimation of acetylcholine esterase in plants. Principle: The hydrolysed acetylcholine per unit time is measured by comparison of the initial concentration in a reference tube with the final concentration in the experimental tube. Acetylcholine is made to react with hydroxylamine to form the corresponding acylhydroxamic acid which forms a strongly [...]