Serum carnosinase

Homocarnosine (Figure 31-2), present in human brain at higher levels than carnosine, is synthesized in brain tissue by carnosine synthetase. Serum carnosinase does not hydrolyze homocarnosine. Homocarnosinosis, a rare genetic disorder, is associated with progressive spastic paraplegia and mental retardation. 

The dynamic profile of carnosine was investigated by comparing MD simulations in isotropic solvents (i.e. water and chloroform) with simulation of the compound bound to serum carnosinase (CNl) [22]. This enzyme is characterized by its distribution in plasma and brain, and its ability to hydrolyze also anserine and homocarnosine [23]. The conformational profile of carnosine can be defined by... 

Vistoli, G., Pedretti, A., Cattaneo, M., Aldini, G., Testa B. Homology modeling of human serum carnosinase, a potential medicinal target, and MD simulations of its allosteric activation by citrate. J. Med. Chem. 2006, 49, 3259-3277. 

There is one explorative study investigating whether there is any correlation between serum carnosinase levels and dementia. The findings, using a small sample size, indicate that while there was no significant... 

Serum carnosinase activities in central nervous system disorders. Clin. Chim. Acta 225, 57-64. 

Serum carnosinase activity is readily measured as a marker for carnosinosis, homocarnosinosis and in instances of jS-alanine elevation in physiological fluids [7]. For quantification, carnosine is incubated with sera samples, and the histidine liberated in the reaction is quantified as the fluorescent o-phthalaldehyde derivative [19]. To estimate the activity of methylmalonate semialdehyde dehydrogenase (direct enzyme determination methods have not been reported), fibroblast extracts are incubated with l-14C-/ -alanine and trapping of 14C02. 

Schoen P, Everts H, de Boer T, van Oeveren W (2003) Serum carnosinase activity in plasma and serum validation of a method and values in cardiopulmonary bypass surgery. Clin Chem 49 1930-1932... 

Serum carnosinase deficiency. This relatively rare disease described in children becomes apparent as camosinemia and camosinurea (increased camosine level in blood and urea). This is caused by very low activity of semm carnosinase which in half of the cases analyzed was characterized by sufficiently elevated Km for substrates [108]. From 23 sick children (belonging to different families) 14 were found to have neurological lesions, myoclonal convulsions, mental retardation at the same time, the correlation between intensity of neurological disorders and residual activity of carnosinase was not found [108]. 

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