Biochemistry I

Lecture  7                                                                       2009 (J.S.)















Alanine - by transamination.

Serine  - by deamination catalyzed of dehydratase (hydrolyase).

Glycine - by accepting one-carbon group gives serine.

Threonine - by splitting gives glycine that may give serine.





























At present, high concentration of homocysteine in blood plasma is included among other biochemical
markers of cardiovascular diseases – as a risk factor for atherosclerosis that is quite independent
on the concentration of cholesterol.



































































is a defect in phenylalanine hydroxylase, the ability to convert Phe to tyrosine is considerably
impaired.

PKU have to be recognized through the

compulsory screening of newborn infants

and treated by a low-phenylalanine diet till the age of 8 – 10 years.

The consequence of untreated PKU is mental retardation (oligophrenia phenylpyruvica). Besides high
levels of blood Phe, alternative catabolites are produced and excreted in high amounts

(a "mousy" odour of the urine) :



is an inborn deficit of homogentisate

oxidase characterized by the excretion  of homogentisate in the urine. Except for the darkening of
the urine on the air, there are no clinical manifestations in youth until the second or third
decade,

when deposits of pigments in the connective tissue begins to appear (ochronosis – bluish colouring
of the scleras, the ear and nasal cartilages, etc.) which are the cause of deforming

arthritis.