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[Amino acid sequence of the protein in a pure proteinic calculus]
I Fernández González1, F Lovaco Castellano, G Giménez Gallego
1Hospital Universitario de Getafe, Madrid, España.
Objective:
The fact that for an equivalent oversaturation of solutes, urine of lithiasic patients has a greater tendency to form crystals, indicate that urine of stone-formers may contain substances that promote crystallization.
Methods:
A renal calculus was analyzed by infra-red spectrophotometry, x-ray dispersion energy spectrophotometry, ultraviolet absorption spectrophotometry, acid hydrolysis cationic exchange chromatography, SDA-Page gel electropheresis with Coomassie Blue and amino acid sequence.
Results:
It was a pure protein calculus formed by a beta 2-microglobulin anomaly. It was a residue that had lost its first 19 amino acids and phenylalanine replaced serine in position 19
Conclusions:
Changes in the amino acid sequence of urinary proteins can cause these to behave like urinary calculus-promoting substances.