RESUMO
Malate dehydrogenase (MDH) plays crucial roles in energy and cellular metabolism. In this study, we describe the identification and characterization of cytosolic MDH (MDH1) and mitochondrial MDH (MDH2) in liver of domestic cat (Felis catus). To clone the feline full-length MDH genes, we performed rapid amplification of cDNA ends. The MDH1 gene encoded a protein of 334 amino acids and the MDH2 gene encoded a protein of 338 amino acids, containing a 24-amino acid mitochondrial target sequence. The feline MDH1 and MDH2 proteins shared, respectively, 98.8-93.7 and 96.7-94.4% homology with dog, giant panda, horse, cow, pig, human, mouse, and rat. The feline MDHs had a highly conserved active motif, which contained important residues for catalysis and coenzyme binding. The putatively acetylated lysine residues that regulate MDH activity were also conserved at K118, K121, and K298 in MDH1, and K185, K301, K307, and K314 in MDH2. Both MDH1 and MDH2 mRNAs were ubiquitously expressed, but these expression levels varied in a tissue-specific manner. Both MDH genes were expressed at considerably high levels in heart and skeletal muscle, but at low levels in lung and spleen.
Assuntos
Citosol/enzimologia , Perfilação da Expressão Gênica , Regulação Enzimológica da Expressão Gênica , Malato Desidrogenase/genética , Mitocôndrias/enzimologia , Sequência de Aminoácidos , Animais , Sequência de Bases , Biocatálise , Gatos , Clonagem Molecular , DNA Complementar/química , DNA Complementar/genética , Isoenzimas/genética , Isoenzimas/isolamento & purificação , Isoenzimas/metabolismo , Lisina/genética , Lisina/metabolismo , Malato Desidrogenase/isolamento & purificação , Malato Desidrogenase/metabolismo , Dados de Sequência Molecular , Músculo Esquelético/enzimologia , Músculo Esquelético/metabolismo , Especificidade de Órgãos/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de DNA , Homologia de Sequência de AminoácidosRESUMO
The aim of this study was to present clear evidence of a stress concentration in bone as a two-phase composite of a collagen matrix reinforced by hydroxyapatite (HAP) mineral particles. X-ray diffractometry was performed on cortical bone from a bovine femur in order to measure strain in HAP along the c-axis as a response to a macroscopically applied force. From the obtained strain of HAP, the stress applied to HAP particles was determined by using Young's modulus value of HAP in the literature. Dividing the stress of HAP by that macroscopically applied to a bone specimen, the stress concentration coefficient, Chi H, was estimated. Using the Hirsch equation with the estimated Chi H, value, mineral content of bone was estimated, which accords with the mineral content values of bone in the literature.