(S)-2,2,5,5-Tetramethylthiazolidine-4-carboxylic acid: a compound which exists in the amino acid rather than the zwitterion form

1985 ◽  
Vol 63 (9) ◽  
pp. 2411-2419 ◽  
Author(s):  
Helen Elaine Howard-Lock ◽  
Colin James Lyne Lock ◽  
Philip Stuart Smalley
Keyword(s):  
Amino Acid ◽  
Carboxylic Acid ◽  
Raman Spectra ◽  
Cooh Group ◽  
Infrared And Raman Spectra ◽  
Acid Form ◽  
Hydrogen Atoms ◽  
Cell Dimensions ◽  
Amino Acid Form ◽  
C Nmr

The X-ray crystal structure of (S)-2,2,5,5-tetramethylthiazolidine-4-carboxylic acid, 1, has been determined. Crystals are monoclinic, P21, with cell dimensions a = 11.351(4) b = 8.303(2), c = 11.969(3) Å, β = 116.69(2)°, and Z = 4. The structure was solved by standard methods and refined to R1 = 0.0774, R2 = 0.0670 for 2388 independent reflections. Compound 1 exists in the amino-acid form as shown by two distinctly different C—O bond lengths, 1.209 and 1.309 Å, typical of the COOH group, and by the positions of the hydrogen atoms. The amino-acid form of 1 found in the solid also exists in solution as shown by infrared and Raman spectra. The mass spectra, and 1H and 13C nmr spectra are reported, as well as detailed infrared and Raman spectra for the title compound and several deuterated species.

scholarly journals 2′-Fluoropyrimidine RNA-based Aptamers to the 165-Amino Acid Form of Vascular Endothelial Growth Factor (VEGF165)

1998 ◽  
Vol 273 (32) ◽  
pp. 20556-20567 ◽  
Author(s):  
Judy Ruckman ◽  
Louis S. Green ◽  
Jim Beeson ◽  
Sheela Waugh ◽  
Wendy L. Gillette ◽  
...  
Keyword(s):  
Vascular Endothelial Growth Factor ◽  
Amino Acid ◽  
Growth Factor ◽  
Vascular Endothelial ◽  
Acid Form ◽  
Amino Acid Form ◽  
Endothelial Growth Factor

Amino-acid zwitterion equilibria: vibrational and nuclear magnetic resonance studies of methyl-substituted thiazolidine-4-carboxylic acids

1986 ◽  
Vol 64 (6) ◽  
pp. 1215-1219 ◽  
Author(s):  
H. E. Howard-Lock ◽  
C. J. L. Lock ◽  
M. L. Martins ◽  
P. S. Smalley ◽  
R. A. Bell
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Amino Acid ◽  
Magnetic Resonance ◽  
Infrared Spectra ◽  
Nmr Spectra ◽  
Infrared And Raman Spectra ◽  
Solid Samples ◽  
Magnetic Resonance Studies ◽  
Cysteine Hydrochloride ◽  
C Nmr

Infrared and Raman spectra (4000–100 cm−1) of solid samples of six different methyl substituted thiazolidine products of D-penicillamine and L-cysteine hydrochloride have been observed and assigned. Infrared spectra in D2O solutions have been obtained for comparison in order to study the amino-acid zwitterion equilibria. Proton and 13C nmr spectra for the compounds have also been measured.

scholarly journals Rules for designing protein fold switches and their implications for the folding code

2021 ◽  
Author(s):  
Yingwei Chen ◽  
Yanan He ◽  
Biao Ruan ◽  
Eun Jung Choi ◽  
Yihong Chen ◽  
...  
Keyword(s):  
Amino Acid ◽  
Single Amino Acid ◽  
Acid Form ◽  
State Behavior ◽  
Amino Acid Region ◽  
Highly Sensitive ◽  
Amino Acid Form ◽  
The Stability ◽  
Similar Conformation ◽  
Acid Region

We have engineered switches between the three most common small folds, 3a, 4b+a, and a/b plait, referred to here as A, B, and S, respectively. Mutations were introduced into the natural S protein until sequences were created that have a stable S-fold in their longer (~90 amino acid) form and have an alternative fold (either A or B) in their shorter (56 amino acid) form. Five sequence pairs were designed and key structures were determined using NMR spectroscopy. Each protein pair is 100% identical in the 56 amino acid region of overlap. Several rules for engineering switches emerged. First, designing one sequence with good native state interactions in two folds requires care but is feasible. Once this condition is met, fold populations are determined by the stability of the embedded A- or B-fold relative to the S-fold and the conformational propensities of the ends that are generated in the switch to the embedded fold. If the stabilities of the embedded fold and the longer fold are similar, conformation is highly sensitive to mutation so that even a single amino acid substitution can radically shift the population to the alternative fold. The results provide insight into why dimorphic sequences can be engineered and sometimes exist in nature, while most natural protein sequences populate single folds. Proteins may evolve toward unique folds because dimorphic sequences generate interactions that destabilize and can produce aberrant functions. Thus two-state behavior may result from nature's negative design rather than being an inherent property of the folding code.

Bis((S)-5,5-dimethylthiazolidine-4-carboxylic acid) protium chloride hydrate [(C6H11NO2S)2H]Cl•H2O, a salt containing a hemi-protonated zwitterion

1987 ◽  
Vol 65 (4) ◽  
pp. 878-883 ◽  
Author(s):  
H. E. Howard-Lock ◽  
C. J. L. Lock ◽  
M. L. Martins ◽  
R. Faggiani ◽  
M. Duarte
Keyword(s):  
Carboxylic Acid ◽  
Mass Spectra ◽  
Crystallographic Position ◽  
Compound I ◽  
Carboxylate Oxygen ◽  
Cell Dimensions ◽  
Short Hydrogen Bond ◽  
Characteristic Features ◽  
Chloride Hydrate ◽  
C Nmr

The X-ray crystal structure of bis((S)-5,5-dimethylthiazolidine-4-carboxylic acid) protium chloride hydrate, I, has been determined. Crystals are orthorhombic, P212121, with cell dimensions a = 6.463(2), b = 11.832(3), c = 23.966(6) Å, and Z = 4. The structure was solved by standard methods and refined to R = 0.073, Rw = 0.064 for 2969 independent reflections. Compound I is composed of two zwitterion molecules bridged through a proton which causes a very short hydrogen bond, O … O′ = 2.450 Å. The proton is located roughly halfway between the two carboxylate oxygen atoms, but is not on a special crystallographic position. Characteristic features of the infrared and Raman spectra, mass spectra, and 1H and 13C nmr spectra are discussed.

scholarly journals Quality Controlled Radiocarbon Dating of Bones and Charcoal from the Early Pre-Pottery Neolithic B (PPNB) of Motza (Israel)

Radiocarbon ◽  
2005 ◽  
Vol 47 (2) ◽  
pp. 193-206 ◽  
Author(s):  
Meirav Yizhaq ◽  
Genia Mintz ◽  
Illit Cohen ◽  
Hamudi Khalaily ◽  
Steve Weiner ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Amino Acid ◽  
Raman Spectra ◽  
Radiocarbon Dating ◽  
Clay Content ◽  
Bone Collagen ◽  
Infrared And Raman Spectra ◽  
Amino Acid Compositions ◽  
Bone Preservation ◽  
Acid Treatments

Radiocarbon dating of early Pre-Pottery Neolithic B (PPNB) deposits at the site of Motza, Israel, was achieved by first prescreening many charcoal and bone samples in order to identify those that are in the most suitable state of preservation for dating. For assessing bone preservation, we determined the collagen contents, and by infrared spectroscopy the collagen purity. The collagen samples of the best preserved bones were then further characterized by their C/N ratios and amino acid compositions. Prescreening of the charcoal samples involved monitoring the changes in infrared and Raman spectra during the acid-alkali-acid treatments. In some samples, we noted that the clay content increased with additional alkali treatments. These samples were rejected, as this could result in erroneous dates. No differences were observed in the 14C dates between charcoal and bone collagen samples. The dates range from 10,600–10,100 cal BP, which is consistent with dates for the early PPNB from other sites. This is of much interest in terms of better understanding where and when domestication of animals began in this period, and how agriculture spread throughout the Levant.

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