Tyrosine probes

A fourth approach to evaluating the intactness of dopamine and/or serotonin neurons in human subjects who have taken one of the amphetamine analogs might be to use a probe for labeling a constituent of those neurons in position emission tomography scanning studies. A label for the serotonin or dopamine uptake carrier, or a label for tryptophan hydroxylase or tyrosine... 

Figure 3.35 presents TR spectra obtained with varying time delays between the pump and probe pulses following photolysis of HbCO. The Raman band features have been attributed to tyrosine (Y) and tryptophan (W) vibrational modes as indicated at the top of Figure 3.35. These Raman bands change with time and provide information about the environment of the typrosine and tryptophan residues in the heme. Inspection of Figure 3.35 reveals that the negative difference Raman...

Fig. 15. Miscellaneous photoaffinity probes for studying interactions in tyrosine kinase, calmodulin and nitric oxide related signaling...

Tyrosine as an Excited-State Probe for Conformation and Dynamics... 

Figure 11 Unnatural amino acids to probe the inactivation mechanism of ion channel Kv1.4. OMeTyr or dansylalanine extends the side chain length of tyrosine, which impedes the inactivation peptide from threading through the side portal of the ion channel and abolishes the fast inactivation, as shown in the current-time curve in the bottom panel.

The hydroxyl radical is a small, highly reactive probe that is formed in water and primarily targets hydrophobic residues [109]. This may be an ideal probe for protein-protein interactions because tyrosine, tryptophan and phenylalanine are most likely to be found at an interface [110, 111]. Although protein-DNA interfaces are comprised of charged and hydrogen-bond donor side-chains, even these residues may be probed by hydroxyl radicals [112]. 

Genistein (64), an isoflavone found in plants of the family Legu-minosae, is an inhibitor of several protein tyrosine kinases (PTK) and is currently in phase II clinical trials for its potential as an angiogenesis inhibitor. Genistein also has been utilized as a probe to identify binding sites for PTKs by observing the effect it demonstrates on cyclic-nucleotide-gated channels. ... 

MolokanovaE, Kramer RH, Mechanism of inhibition of cyclic nucleotide-gated channel by protein tyrosine kinase probed with genistein, J Gen Physiol 117 219-234, 2001. 

S.-C. Huang, J. Quintana, N. Satyamurthy, G. Lacan, D.-C. Yu, M.E. Phelps, J.R. Barrio, [ F]Fluoro- -fluoromethylene-m-tyrosine derivatives show stereo, geometrical, and regio specificities as in vivo central dopaminergic probes in monkeys, Nucl. Med. Biol. 26 (1999) 365-370. 

Aromatic amino acids are biogenetic precursors of neuroamines (dopamine, serotonin, histamine, etc.). On the other hand, phenylalanine (Phe) is frequently present in peptide sequences, while tyrosine is an important site of phosphorylation of proteins. Aromatic amino acids and neuroamines fluorinated on the aromatic ring have been the focus of many investigations. Indeed, after incorporation in polypeptides and proteins, they can be used as probes in NMR and in PET. 

A suitable fiuorescent probe is an organic molecule, which must change its characteristic parameters with changes in its microenvironment and the parameter must be measurable when the probe is added to the system [54]. The fluorescent probes are categorized as either extrinsic, intrinsic, or covalently bound probes. The intrinsic probes allow a system to be observed without any chemical perturbation. This occurs when the system to be characterized has an in-built fluorescent chromophore unit like tryptophan, tyrosine and phenyl alanine in protein. In some cases the fluorophore is covalently... 

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