Pathways

Streptokinase is a bacterial protein that is fibrinolytic and used to break down blood clots in myocardial infarction, pulmonary embolism and venous thromboembolism. It is administered intravenously and travels through the bloodstream to target blood clots. Streptokinase does this by converting plasminogen to its active form plasmin, by cleaving an arginine-valine bond. Once plasmin is activated it breaks down the fibrin mesh of the blood clot turning it into degradation products. Due to the anticoagulant and antiplatelet activity, herbs and supplements with a similar activity should be avoided such as garlic, ginger, bilberry, danshen, piracetam and ginkgo biloba.

Streptomycin (also named Gerox or Agrimycin) is an aminoglycoside antibiotic for the treatment of bacteria infections by inhibiting the synthesis of bacterial proteins. Streptomycin reversibly binds to 16S rRNA and the bacterial 30S ribosomal subunit so that the initiation complex with mRNA couldn't be formed. Binding of streptomycin on 16S rRNA's four nocleotides will lead to misreading of mRNA which result in insertion of incorrect amino acids into polypeptide. Nonfunctional or toxic peptides will lead to nonfunctional monosomes. Aminoglycosides are useful primarily in infections involving aerobic, Gram-negative bacteria, such as Pseudomonas, Acinetobacter, and Enterobacter. In addition, some mycobacteria, including the bacteria that cause tuberculosis, are susceptible to aminoglycosides. Infections caused by Gram-positive bacteria can also be treated with aminoglycosides, but other types of antibiotics are more potent and less damaging to the host. In the past the aminoglycosides have been used in conjunction with penicillin-related antibiotics in streptococcal infections for their synergistic effects, particularly in endocarditis. Aminoglycosides are mostly ineffective against anaerobic bacteria, fungi and viruses.

Streptomycin is an antibiotic that treats multi-drug-resistant bacterial strains. It is in the aminoglycosides family and it is derived from Streptomyces griseus which was the first effective antibiotic against Mycobacterium tuberculosis. It is now largely a second-line option due to the development of resistance and toxicity. Streptomycin goes through 3 phases in order to infiltrate the bacterial cell and inhibit protein synthesis: the first phase is the binding of polycationic drug to the negatively charged bacterial cell membrane which increases membrane permeability. The second phase is the entry of aminoglycoside through oxygen-dependent active transport into the cell where it then travels and binds to the 16rRNA and 30S ribosomal subunit. The final phase is the inhibition of protein synthesis and the accumulation of Streptomycin in the cell which further exacerbates its inhibition of protein synthesis, elongation, and ribosome recycling. It is mainly used in combination with other antibiotics. It is commonly administered via intramuscular injection or intravenously and is eliminated in the urine 24 hours after its administration into the body. Some caution must be taken with streptomycin as overdose can lead to nephrotoxicity and ototoxicity.

Streptomycin, an antibiotic discovered in 1943, belongs to a class of drugs called aminoglycoside antibiotics. It is produced by Streptomyces griseus, a soil residing bacteria, and its role is to inhibit translation by interfering with the growth of the bacteria by inducing prokaryotic ribosomes to misread mRNA. This pathway shows the biosynthesis of streptomycin in a bacterial cell of Streptomyces griseus originating from a D-glucose compound. There are three branches to this pathway that give rise to the functional unit monomers: streptidine 6-phosphate, dTDP-L-dihydrostreptose and NDP-N-methyl-L-glucosamine, that streptomycin is made up of. The first branch on the left is involved in the eventual synthesis of the streptidine 6-phosphate intermediate which in this pathway has been shortened to show an intermediate upstream of it: amidino-scyllo-inosamine-4P synthesized via the protein scyllo-inosamine-4-phosphate amidinotransferase. The second branch in the center is involved in the synthesis of the monomer dTDP-L-dihydrostreptose synthesized via the protein putative dTDP-4-dehydrorhamnose 3,5-epimerase. The third branch on the right is involved in the synthesis of the monomer NDP-N-methyl-L-glucosamine from glucose-1-phosphate and no protein is involved in this reaction. The intermediates/monomeric units streptidine 6-phosphate and dTDP-L-dihydrostreptose are then involved in a reaction catalyzed by the protein putative dTDP-dihydrostreptose--streptidine-6-phosphate dihydrostreptosyltransferase to give rise to the intermediate O-(1->4)-alpha-L-dihydrostreptosyl-streptidine 6-phosphate and dTDP. O-(1->4)-alpha-L-dihydrostreptosyl-streptidine 6-phosphate along with NDP-N-methyl-L-glucosamine give rise to dihydrostreptomycin-6P and nucleoside diphosphate. Dihydrostreptomycin-6P reacts to form streptidine 6-phosphate again which reacts in a cyclic manner to form streptomycin. Streptomycin is then exported out of the cell to then be extracted as a useful antibiotic.

Streptozocin is a drug that is not metabolized by the human body as determined by current research and biotransformer analysis. Streptozocin passes through the liver and is then excreted from the body mainly through the kidney.

stress signal is sensed by membrane protein pknB and phophorylate the sigH

Stress-activated protein kinase pathways in Saccharomyces. The HOG1 MAPK pathway is controlled by two separate osmosensors, SLN1 and SHO1. Sln1 is activated in low osmolarity, thus repressing Ssk1 by phosphorylating it. Ssk1 is in charge of activating Ssk2/22 which in turn activates Pbs2 and in turn activates Hog1. SHO1 is activated during high osmolarity, resulting in Ste11 being activated, which in turn activates Pbs2 and activates Hog1. Ptp2 and Ptp3 negatively regulates Hog1.