Structural and Functional Analysis of the Amorphous Calcium Carbonate-Binding Protein Paramyosin in the Shell of the Pearl Oyster, Pinctada fucata

Amorphous calcium carbonate (ACC) is an important precursor phase for the formation of aragonite crystals in the shells of Pinctada fucata. To identify the ACC-binding protein in the inner aragonite layer of the shell, extracts from the shell were used in the ACC-binding experiments. Semiquantitative analyses using liquid chromatography-mass spectrometry revealed that paramyosin was strongly associated with ACC in the shell. We discovered that paramyosin, a major component of the adductor muscle, was included in the myostracum, which is the microstructure of the shell attached to the adductor muscle. Purified paramyosin accumulates calcium carbonate and induces the prism structure of aragonite crystals, which is related to the morphology of prism aragonite crystals in the myostracum. Nuclear magnetic resonance measurements revealed that the Glu-rich region was bound to ACC. Activity of the Glu-rich region was stronger than that of the Asp-rich region. These results suggest that paramyosin in the adductor muscle is involved in the formation of aragonite prisms in the myostracum.

Structural Analyses of DP-1, a Protein with the Ability To Bind Gold Nanoparticles, by Using Nuclear Magnetic Resonance Spectroscopy

Gold nanoparticles (AuNPs), consisting of metallic gold, are applied in various fields owing to their characteristic physical properties. Collimonas sp. D-25 (D-25) is a Gram-negative bacterium obtained from soil, compost, and other environmental materials in the Akita Prefecture. DP-1 is a water-soluble protein found in D-25 that binds specifically to AuNPs and retains them with high stability. This study aimed to identify the part of DP-1 that interacts with AuNPs and determine its 3D structure in solution using nuclear magnetic resonance spectroscopy. Peptide fragments obtained by trypsin digestion were examined for their AuNP-binding capacity to determine the key Au-binding domain of DP-1. A fragment consisting of 16 amino acid residues (GHAATPEQYGVVTANK) was identified as the peptide with the highest binding activity. Structural analyses of this peptide indicated that the main chain was elongated, and negatively charged residues in the side chain were exposed on the surface by incorporating AuNPs. These results suggest that DP-1 interacts with AuNPs through negatively charged residues and extended hydrophobic residues for protein-protein interactions. The structural data also provide new insights into biomimetic technologies.

[Anesthetic management of a patient with dilated cardiomyopathy using olprinone]

A 51-year-old man with dilated cardiomyopathy, who had been treated with medication for five years, was scheduled for abdomioperineal resection of the rectum. Preoperative echocardiography demonstrated left ventricular dilation and hypertrophy, with an ejection fraction of 0.34. Anesthesia was induced with ketamine 40 mg and fentanyl 0.5 mg intravenously. Endotracheal intubation was facilitated by administration of vecuronium 10 mg. Anesthesia was maintained with nitrous oxide-oxygen-sevoflurane and fentanyl. In order to regulate myocardial contractility and after-load, use of a phosphodiesterase III inhibitor was considered, although phosphodiesterase III inhibitors are known to induce arrhythmias, which should be avoided in dilated cardiomyopathy patients. We chose olprinone, because its inotropic action is not associated with arrhythmogenecity. Before infusing olprinone, cardiac output was 4.5 l.min-1 and systemic vascular resistance was 1306 dynes.sec.cm-5. When olprinone was continuously infused for one hour, cardiac output increased to 5.2 l.min-1 and systemic vascular resistance decreased to 958 dynes.sec.cm-5. Some premature ventricular contractions occurred, but they were easily controlled by administration of 50 mg lidocaine. These clinical data demonstrate that olprinone enhanced myocardial contractility, and decreased after-load and arrhythmogenecity in a dilated cardiomyopathy patients. In conclusion, olprinone is useful in the perioperative cardiovascular management of surgical patients with dilated cardiomyopathy.