Familial cherubism: clinical and radiological features. Case report and review of the literature.

BACKGROUND: Cherubism is a rare genetic disorder that causes prominence in the lower portion in the face. The authors present the case of an 11-year old boy showing bilateral enlargement of the mandible. CASE REPORT: Computer tomography evidenced the presence of characteristic cherubism changes. The genetic test confirmed heterozygote mutation c.1244G>A (p.R415Q) in second exon coding sequence of SH3BP2 gene. Radiographic examinations performed on some close relatives of the patient revealed typical changes. The patient did not require any surgical treatment and the "wait and see" protocol was applied.

Cleavage of the Arg1-Pro2 bond of bradykinin by a human lung peptidase: isolation, characterization, and inhibition by several beta-lactam antibiotics.

An aminopeptidase P (EC 3.4.11.9) that cleaves the Arg1-Pro2 bond of bradykinin has been isolated for the first time from human lung and purified 473-fold. The enzyme also catalyzes the cleavage of arginine from des-[Arg9]-bradykinin and the hydrolysis of several X-proline dipeptides including L-arginyl-L-proline, L-leucyl-L-proline, and L-alanyl-L-proline. Purified enzyme was routinely assayed (after initial identification with des-[Arg9]-bradykinin) with L-leucyl-L-proline. The molecular weight, in nondenaturing buffers, is 188,000 +/- 8500 Da. The pH optimum was 8.0 with arginyl-proline, and was 6.8 with leucyl-proline. Chelating agents do not inactivate the enzyme, but rather only remove loosely bound cations that stimulate the enzyme. Manganese is the principal cation that stimulates the enzyme. The enzyme is inhibited by several beta-lactam antibiotics, cephalexin and oxacillin being the most effective of those tested. The antibiotic inhibition is time and temperature dependent, and it is not fully reversible by exhaustive dialysis of the antibiotic-treated enzyme.

Kinin cleavage by human erythrocytes.

An aminopeptidase-P has been purified 230-fold from human erythrocytes. The purified enzyme cleaved arginine from des-(Arg9)-bradykinin (Arg-Pro-Pro-Gly-Phe-Ser-Pro-Phe) had a molecular weight in nondenaturing buffers of 155,000 +/- 6,900 daltons, was not inactivated by chelating agents, had a pH optimum of 7.2, and was stimulated by manganous ions. The aminopeptidase-P was stable in intact erythrocytes for at least 21 days. Extensively washed and intact human erythrocytes cleaved arginine from exogenously supplied des-(Arg9)-bradykinin; arginine was the earliest-appearing reaction product. Purified aminopeptidase-P also cleaved a group of X-proline dipeptides including leucyl-proline, methionyl-proline, phenylalanyl-proline, arginyl-proline, and alanyl-proline. The total intra-erythrocytic aminopeptidase-P activity of the "average 70-kg man" was 2,600 units, approximately five times the amount of activity in the total lung mass. The human erythrocyte aminopeptidase-P activity was not tightly bound to the erythrocyte membrane. Intact erythrocytes also exhibited some kinin-converting enzyme activity.

Action of human pancreas alanine aminopeptidase on biologically active peptides: kinin converting activity.

A group of 15 biologically active peptides were studied with respect to their susceptibility to chain shortening by human pancreas alanine aminopeptidase. Those susceptible were somatostatin, melanocyte stimulating hormone, fibrinopeptide A, eosinophilotactictetrapeptide, lysyl-bradykinin, and methionyl-lysyl-bradykinin. The latter two were selected for further study. Direct identification and determination of the reaction products, lysine and/or methionine, were undertaken to establish unequivocally the kinin-converting activity of human pancreas alanine aminopeptidase, which exhibited a pH optimum at pH 7.9. The Km and kcat values for this enzyme for lysyl-bradykinin were 57 mumol/l and 3000 min-1, respectively. The corresponding values for this enzyme for methionyl-lysyl-bradykinin were calculated to be 49 mumol/l and 16000 min-1, respectively. Bradykinin itself is extremely resistant to hydrolysis by this pancreatic enzyme.

Multiple molecular forms of human alanine aminopeptidase: immunochemical properties.

Human pancreas, kidney, and liver alanine aminopeptidases have similar if not identical antigenic determinants even though these three isoenzymes have distinctly different electrophoretic mobilities. Single precipitin lines without spur formation were obtained for all three enzymes with antisera obtained from rabbits immunized with these three purified enzymes. Treatment of these enzymes with neuraminidase eliminated the differences in their electrophoretic migration on polyacrylamide gels and on agarose immunoelectrophoresis gels. Treatment of the pancreas, kidney, and liver alanine aminopeptidases with their respective antibodies yielded enzymes that displayed non-competitive inhibition when the dependence of velocity upon substrate concentration was determined for each enzyme, i.e. the antibodies did not cause a change in the Km values obtained in the absence of the antibody whereas kcat was reduced to the same extent for each enzyme. The removal of sialic acid(s) from these enzymes did not alter their immunochemical characteristics or their kinetic characteristics.

Multiple molecular forms of human pancreas alanine aminopeptidase.

Human pancreas is the source of an alanine aminopeptidase (HPAA) that is unique to pancreas and is readily distinguishable from the liver, kidney, and duodenal alanine aminopeptidases. Each of these three aminopeptidases appears in small quantities in blood and therefore may consitute tissue/organ specific marker enzymes. In this study alanine aminopeptidase from pancreas has been purified. Pancreas alanine aminopeptidase was resolved upon purification with ion exchange chromatography into three isoenzymes. Gel filtration chromatography of these isoenzymes indicates that their molecular weights are near 235 000 daltons. The isoenzymes contain a firmly bound divalent cation that could be removed with EDTA only at temperatures above 40 degrees C (at which the enzymes were stable) and below 52 degrees C (at which thermal denaturation begins to take place). Treatment with EDTA at 4 degrees C yields fully active enzymes, which, however may be stimulated approximately 200% by the addition of Co2+ at 10(-4) mol/l. This cobalt stimulation is easily reversed by dialysis of the stimulated isoenzymes against deionized water. The pancreas alanine aminopeptidases were not inhibited by tosyl-phenylalanine chloromethylketone or by tosylleucine chloromethylketone, whereas phenylalanine chloromethylketone was inhibitory. The Km values for methionyl-, arginyl-, leucyl-, alanyl-, and isoleucyl-beta-naphthylamide for each isoenzyme are statistically identical and the average values are 0.36, 0.60, 0.69, 1.25, and 1.29 X 10(-4) mol/l, respectively. The kcat values are 2.50, 1.58, 0.82, 0.38, and 0.19 X 10(4) sec-1, respectively.