Poorly aligned barrel

Leaks at Demountable Seals. These leaks are caused by wear, old stopcock grease, poorly applied grease, poor alignment, twisted or worn O-rings, inadequate stopcocks or joints, mismatched plugs and barrels, or dirt between pieces. This list is by no means complete, but it gives you an idea of the range of problems. 

The almost concomitant report of the crystal and solution structures from several unliganded SH3 domains (31-36) revealed a completely conserved fold a compact p-barrel, formed by two anti-paraUel, three-stranded p-sheets (Fig. 2A). A structure-based alignment of a subset of SH3 domains is shown in Fig. 2B. The structure starts at the poorly conserved pi strand. After this strand, the polypeptide chain engages in the formation of the so-called RT loop, connecting strands pA and pB (see below for an explanation of this nomenclature). One of the sequence... 

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