BIOINORGANIC CHEMISTRY A Short Course Second Edition

Ion

Radius (

Å )/

Coordination

No.

Concentration (mM)

Carriers, Facilitators, Enzymes,

Cofactors Function/Toxicity

Extracellular

(BloodPlasma)

Intracellular (Red Blood

Cells)

Mg

2+

0.65/6

2

2.5

Ionophores, ATPases, kinases,

enolases, glutamine synthetase, methyl aspartase, ribulose bisphosphate carboxylase, alkaline phosphatase, xylose isomerase, chlorophyll

Nucleic acid stabilization, electrostatics,

structure and potential stabilization or catalysis in enzymes

Ca

2+

0.99/7( ± )

2

10

− 4

Ionophores, Ca - ATPases, EF -

hand proteins, extracellular digestive enzymes, structural/storage proteins

Stabilize skeletal matter, muscle and nerve

triggering, activation of kinases, catalysis

Sr

2+

1.13

Toxicity — replaces calcium in bone,

6

treatment of androgen - independent prostate cancer

7

Ba

2+

1.35

BaSO

used as contrast agent for 4

radiography and MRI and in bone cements used for the fi

xation of joint

prostheses, Ba

2+

inhibits K

+ fl

ux through

potassium ion channels

Ra

2+

1.43

Radiation therapy for carcinomas

Sources

: References 1 and 2.

INTRODUCTION 191