Heat Capacities of L-Cysteine, L-Serine, L-Threonine, L-Lysine, and L-Methionine

Abstract

In an effort to establish reliable thermodynamic data for amino acids, heat capacity and phase behavior are reported for L-cysteine (CAS RN: 52-90-4), L-serine (CAS RN: 56-45-1), L-threonine (CAS RN: 72-19-5), L-lysine (CAS RN: 56-87-1), and L-methionine (CAS RN: 63-68-3). Prior to heat capacity measurements, initial crystal structures were identified by X-ray powder diffraction, followed by a thorough investigation of the polymorphic behavior using differential scanning calorimetry in the temperature range from 183 K to the decomposition temperature determined by thermogravimetric analysis. Crystal heat capacities of all five amino acids were measured by Tian–Calvet calorimetry in the temperature interval (262–358) K and by power compensation DSC in the temperature interval from 215 K to over 420 K. Experimental values of this work were compared and combined with the literature data obtained with adiabatic calorimetry. Low-temperature heat capacities of L-threonine and L-lysine, for which no or limited literature data was available, were measured using the relaxation (heat pulse) calorimetry. As a result, reference heat capacities and thermodynamic functions for the crystalline phase from near 0 K to over 420 K were developed.

Combining Copper and Zinc into a Biosensor for Anti-Chemoresistance and Achieving Osteosarcoma Therapeutic Efficacy

“…This is because of the Jan-Teller effect in their d-orbitals, copper ions exist in two coordination redox states [22]. Their ligands are cysteine and methionine for S donor atoms [105] and histidine, glutamic acid, and aspartic acid for N or O donor atoms [106]. Because of their copper (I) and copper (II) redox states, they have a higher IC50 value and inhibitory activity, resulting in greater potency, clinical effectiveness, and less toxicity than other anti-proliferative drugs [56] [107].…”

“…The copper-induced mutation of the binding motif ULK-1 and ULK2 (ULK1/2) [167] impairs the ULK1/2-dependent signalling pathway [189]. The amino acid sequence of ULK1/2 is similar to that of serine/tyrosine/threonine kinases (MEK)-1 [105], which comprises high-affinity copper (II) binding with histidine (H)-188, methionine (M)-230, and H-239 [190]. MEK1 induces ERK phosphorylation [191] that will activate MAPK in tumours such as RAS and RAF.…”

Combining Copper and Zinc into a Biosensor for Anti-Chemoresistance and Achieving Osteosarcoma Therapeutic Efficacy

“…This is because of the Jahn–Teller effect in their d-orbitals; copper ions exist in two coordination redox states [ 22 ]. Their ligands are cysteine and methionine for S donor atoms [ 100 ] and histidine, glutamic acid, and aspartic acid for N or O donor atoms [ 101 ]. Due to their copper(I) and copper(II) redox states, they have a higher IC 50 value and inhibitory activity, resulting in greater potency, clinical effectiveness, and less toxicity than other anti-proliferative drugs [ 53 , 102 ].…”

“…The copper-induced mutation of the binding motif ULK-1 and ULK2 (ULK1/2) [ 168 ] impairs the ULK1/2-dependent signalling pathway [ 190 ]. The amino acid sequence of ULK1/2 is similar to that of MEK-1 [ 100 ], which comprises high-affinity copper(II) binding with histidine (H)-188, methionine (M)-230, and H-239 [ 191 ]. MEK1 induces ERK phosphorylation [ 192 ] that will activate MAPK in tumours such as RAS and RAF.…”

Saturated Vapor Pressure and Sublimation Enthalpy of l-serine and l-cysteine

“…Thermodynamic Functions H°(T) − H°(0)/(kJ mol −1 ) and Φ°(T)/(J mol −1 K −1 ) a Note. The relative standard uncertainties u r in thermodynamic functions are estimated to be 0.02 of the absolute value for ideal gas21 and 0.02 for crystal 8. …”