Bioinorganic Chemistry

A Short Course

Rosette M. Roat-Malone

• Editore: Wiley
• Anno: 2020
• ISBN:
  9781119535263
• Edizione: 3
• Argomento: Biological Sciences
• Categoria: Biochemistry

Introduces students to the basics of bioinorganic chemistry

This book provides the fundamentals for inorganic chemistry and biochemistry relevant to understanding bioinorganic topics. It provides essential background material, followed by detailed information on selected topics, to give readers the background, tools, and skills they need to research and study bioinorganic topics of interest to them. To reflect current practices and needs, instrumental methods and techniques are referred to and mixed in throughout the book.

Bioinorganic Chemistry: A Short Course, Third Edition begins with a chapter on Inorganic Chemistry and Biochemistry Essentials. It then continues with chapters on: Computer Hardware, Software, and Computational Chemistry Methods; Important Metal Centers in Proteins; Myoglobins, Hemoglobins, Superoxide Dismutases, Nitrogenases, Hydrogenases, Carbonic Anhydrases, and Nitrogen Cycle Enzymes. The book concludes with chapters on Nanobioinorganic Chemistry and Metals in Medicine. Readers are also offered end-of-section summaries, conclusions, and thought problems.

• Reduces size of the text from previous edition to match the first, keeping it appropriate for a one-semester course
• Offers primers and background materials to help students feel comfortable with research-level bioinorganic chemistry
• Emphasizes select and diverse topics using extensive references from current scientific literature, with more emphasis on molecular biology in the biochemistry section, leading to a discussion of CRISPR technology
• Adds new chapters on hydrogenases, carbonic anhydrases, and nitrogen cycle enzymes, along with a separate chapter on nanobioinorganic chemistry
• Features expanded coverage of computer hardware and software, metalloenzymes, and metals in medicines
• Supplemented with a companion website for students and instructors featuring Powerpoint and JPEG figures and tables, arranged by chapter

Appropriate for one-semester bioinorganic chemistry courses, Bioinorganic Chemistry: A Short Course, Third Edition is ideal for upper-level undergraduate and beginning graduate students. It is also a valuable reference for practitioners and researchers in need of a general introduction to the subject, as well as chemists requiring an accessible reference.

1
INORGANIC CHEMISTRY AND BIOCHEMISTRY ESSENTIALS

1.1 INTRODUCTION

Bioinorganic chemistry involves the study of metal species in biological systems. As an introduction to the basic inorganic chemistry is needed for understanding bioinorganic topics, this chapter will discuss the essential chemical elements, the occurrences and purposes of metal centers in biological species, the geometries of ligand fields surrounding these metal centers and ionic states preferred by the metals. The occurrence of organometallic complexes and clusters in metalloproteins will be discussed briefly and an introduction to electron transfer in coordination complexes will be presented. Since the metal centers under consideration are found in a biochemical milieu, basic biochemical concepts, including a discussion of proteins and nucleic acids, are presented later in this chapter.

1.2 ESSENTIAL CHEMICAL ELEMENTS

Chemical elements essential to life forms can be broken down into four major categories: (i) bulk elements (H/H⁺, C, N, O²⁻/O₂^−·/O₂²⁻, P, and S/S²⁻); (ii) macrominerals and ions (Na/Na⁺, K/K⁺, Mg/Mg²⁺, Ca/Ca²⁺, Cl⁻, PO₄³⁻, and SO₄²⁻); (iii) trace elements (Fe/Fe^II/Fe^III/Fe^IV, Zn/Zn^II, and Cu/Cu^I/Cu^IICu^III); and (iv) ultratrace elements, that comprise nonmetals (F/F⁻, I/I⁻, Se/Se²⁻, Si/Si^IV, As, and B) and metals (Mn/Mn^II/Mn^III/Mn^IV, Mo/Mo^IV/Mo^V/Mo^VI, Co/Co^II/ Co^III, Cr/Cr^III/Cr^VI, V/V^III/ V^IV/ V^V/, Ni^I/ Ni^II/ Ni^III/, Cd/Cd²⁺, Sn/Sn^II/Sn^IV, Pb/Pb²⁺, and Li/Li⁺). In the preceding classification, only the common biologically active ion oxidation states are indicated (see references [1, 2d] for more information). If no charge is shown, the element predominately bonds covalently with its partners in biological compounds, although elements such as carbon (C), sulfur (S), phosphorus (P), arsenic (As), boron (B), and selenium (Se) have positive formal oxidation states in ions containing oxygen atoms; i.e. S = +6 in the SO₄²⁻ ion or P = +5 in the PO₄³⁻ ion. The identities of essential elements are based on historical work done by Klaus Schwarz in the 1970s [3]. Other essential elements may be present in various biological species. Essentiality has been defined by certain criteria: (i) a physiological deficiency appears when the element is removed from the diet; (ii) the deficiency is relieved by the addition of that element to the diet; and (iii) a specific biological function is associated with the element [4]. Table 1.1 indicates the approximate percentages by weight of selected essential elements for an adult human.

Every essential element follows a dose‐response curve, shown in Figure 1.1, as adapted from reference [4]. At lowest dosages, the organism does not survive whereas in deficiency regions the organism exists with less than optimal function. After the concentration plateau of the optimal dosage region, higher dosages cause toxic effects in the organism eventually leading to lethality. Specific daily requirements of essential elements may range from microgram to gram quantities.

Considering the content of earth's contemporary waters and atmospheres, many questions arise as to the choice of essential elements at the time of life's origins 3.5 billion or more years ago. Certainly sufficient quantities of the bulk elements were available in primordial oceans and at shorelines. However, the concentrations of essential trace metals in modern oceans may differ considerably from those found in prebiotic times. Iron's current approximate 10⁻⁴ mM concentration in seawater, for instance, may not reflect accurately its prelife‐forms availability. If one assumes a mostly reducing atmosphere contemporary with the beginnings of biological life, the availability of the more soluble iron(II) ion in primordial oceans must have been much higher. Thus, the essentiality of iron(II) at a concentration of 0.02 mM in the blood plasma heme (hemoglobin) and muscle tissue heme (myoglobin) may be explained. Beside the availability factor, many chemical and physical properties of elements and their ions are responsible for their inclusion in biological systems. These include ionic charge, ionic radius, ligand preferences, preferred coordination geometries, spin pairings, systemic kinetic control, and the chemic...