Inhibition of β-Amylase Activity by Calcium, Magnesium and Zinc Ions Determined by Spectrophotometry and Isothermal Titration Calorimetry

Abstract

The inhibition effect of metal ions on beta amylase activity was studied. The inhibitor-binding constant (Ki) was determined by spectrophotometric and isothermal titration calorimetric (ITC) methods. The binding of calcium, magnesium and zinc ion as inhibitors at the active site of barley beta amylase was studied at pH = 4.8 (sodium acetate 16 mM) and T = 300K. The Ki and enthalpy of binding for calcium (13.4, 13.1 mM and -14.3 kJ/mol), magnesium (18.6, 17.8mM and -17.7 kJ/mol) and zinc (17.5, 17.7 mM and -20.0 kJ/mol) were found by spectrophotometric and ITC methods respectively.

An outlook on suicide enzyme inhibition and drug design

“…Thus, the inhibitor has extra affinity for binding to the enzyme at higher temperature [ 9 ]. The dissociation binding constant ( K i ) could be achieved from thermodynamic and kinetic studies [ 2 ]. Furthermore, aspirin and diclofenac are anti-inflammatory drugs, inhibit (suicide inhibition) the activity of adenosine deaminase (ADA), and have diverse effects at diverse temperatures [ 17 ].…”

“…Commonly, when the effect is to reduce the rate, this is labeled “inhibition” [ 1 ]. The inhibition of enzyme activity is the dominant regulatory tool of living cells and one of the critical diagnostic processes for enzymologists [ 2 ]. This is of great interest in pharmacological studies [ 3 ] and is subject to the condition of interaction between inhibitor, substrate, and enzyme.…”

A Thermodynamic Study on the Binding of Cobalt Ion with Myelin Basic Protein

“…One of the unique aspects of our approach is studying the stability of proteins by using the extended solvation model. Myelin Basic Protein, MBP, is one of the most important proteins of the myelin sheath, 38 and its predominant extrinsic protein in both central and peripheral of the central nervous system myelins. It is thought to be involved in the stabilizing interactions between myelin membranes, and it may play an important role in demyelinating diseases such as multiple sclerosis.…”

“…The extended solvation model satisfactorily reproduces all the experimental enthalpies transfer of the solutes from pure solvents into mixed solvent systems across the whole range of solvent compositions. [37][38][39][40][41][42] Studies within our group are aimed at developing an understanding of how the metal ions and other ligands binding proteins affect on the stability of the biomolecules. One of the unique aspects of our approach is studying the stability of proteins by using the extended solvation model.…”

Estudos estruturais e funcionais da única enzima diadenilato ciclase e da única YbbR-like de <i>Staphylococcus aureus</i>: proteínas envolvidas na biossíntese de c-di-AMP

“…A afinidade Sau_DacA 86 pelo ATP é significativamente maior na presença de Mn +2 (k d = 8 ± 1 μM), mas apenas ligeiramente aumentada na presença dos íons de Co +2 (k d = 27 ± 1 μM) e Fe +2 (k d = 30 ± 3 μM), comparativamente à afinidade encontrada na ausência destes íons metálicos.Interessantemente, Mg +2 e Zn +2 não aumentam a afinidade da proteína pelo ATP de maneira estatisticamente relevante (k d = 37 ± 11 μM e k d = 38 ± 5 μM, respectivamente), ao passo que íons de cálcio provocam efeito contrário, ou seja, diminuem a afinidade da proteína pelo nucleotídeo. Já é bem conhecido que íons de cálcio podem inibir ciclases através de ligação no sítio de ligação do cofator efetivo da proteína de interesse através de impedimento estérico de coordenação do cofator no sítio de ligação ou em sítios alostéricos de regulação de atividade da proteína [114][115][116][117][118]. Logo como não se tem conhecimento da existência de sítios alostéricos de regulação das diadenilato ciclases, até o momento, podemos sugerir que o íon cálcio diminui a afinidade da Sau_DacA 86 pelo ATP através de impedimento estérico do sítio de coordenação do cofator efetivo da Sau_DacA 86 .…”