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Iron rings used in a laboratory. An iron ring or ring clamp is an item of laboratory equipment which comprises a conjoined metal ring and radially-extending rod. [1] In some cases, the rod terminates in a screw clamp for attachment to a retort stand or other support; in others, the rod may be attached to a stand by means of a laboratory clamp holder. [2]
The critical functional groups of rifampicin in its inhibitory binding of bacterial RNA polymerase are the four critical hydroxyl groups of the ansa bridge and the naphthol ring, which form hydrogen bonds with amino acid residues on the protein. [40] Rifampicin is the 3-(4-methyl-1-piperazinyl)-iminomethyl derivative of rifamycin SV. [41]
While the ring closure in penams and cephems is between positions 1 and 4 of the β-lactam and is oxidative, the clavams and carbapenems have their rings closed between positions 1 and 2 of the ring. β-lactam synthetases are responsible for these cyclizations, and the carboxylate of the open-ring substrates is activated by ATP. [35]
[9] [10] If rifamycin binds the polymerase after the chain extension process has started, no inhibition is observed on the biosynthesis, consistent with a steric-occlusion mechanism. Single step high level resistance to the rifamycins occurs as the result of a single amino acid change in the bacterial DNA dependent RNA polymerase.
Marman clamps are used extensively in spaceflight systems and are common mechanical load-transfer and clamping mechanisms for connecting the upper stage and the satellite payload of space vehicles, [3] [4] for example, on the Cassini Plasma Spectrometer on the Cassini orbiter. They may also be used to join stages of a booster rocket.
They are bicyclic ring systems containing a β-lactam moiety fused with a five-member thiazolidine ring. [1] Due to ring strain and limitations on amide resonance, the structure is unstable and highly susceptible to catalytic cleavage at the amide bond. [2] Benzylpenicillin (penicillin G) is the natural product parent that contains the penam ...
Rifapentine, sold under the brand name Priftin, is an antibiotic used in the treatment of tuberculosis. [2] In active tuberculosis it is used together with other antituberculosis medications. [2]
It is a fixed dose combination of rifampicin, isoniazid, and pyrazinamide. [1] It is used either by itself or along with other antituberculosis medication. [1] It is taken by mouth. [1] Side effects are those of the underlying medications. [1] These may include poor coordination, loss of appetite, nausea, joint pain, feeling tired, and numbness ...