Metals in Medicines Flashcards
What is a covalent bond? Give examples
sharing of electrons
eg peptide bonds, ligand to metal bonds
What is a ionic bond? Give examples
association of positively and negatively charged species
eg salt bridges, association of hard cations and hard ligands
What is a hydrogen bond? Give examples
H atom shared between two highly electronegative atoms
eg base-base interactions in DNA, a-helixes in proteins
What are Van der Wals forces? Give examples
large number of atoms reinforcing transient weak polarising effects
ef intercalation between DNA base pairs
What is a coordinative/dative bond?
covalent bond in which both electrons come from the same donor atom/ligand
How do you determine oxidation state of a metal centre?
- determine overall charge by looking at cation
- assign charges to ligands (most are neutral)
- determine difference in charge between overall cation and ligands
What are examples of ligands?
- oxygen atoms from H2O, OH-, OR-
- single charged anions F-, Cl-
- neutral ligands like NH3, CO
- sulphur atoms from residues like RSH
What are favoured combinations of cations and donor centres?
- Calcium 2+ - only O donors eg Ca binding proteins
- Mg 2+ - O donors preferred ef phosphate groups in DNA, RNA
- Zinc 2+ - N,O,S eg Zn-dependent endopeptodiases
What is the coordination number?
number of ligands surrounding a metal centre in a complex
What is the geometry for different coordination numbers?
3: trigonal planar
4: tetrahedral or square planar
5: trigonal bipyramid or square pyramid
6: octahedral
What is a trace element?
dietary element that is needed for proper growth, development and physiology of organism
What happens when theres an imbalance of Fe, Zn, Cu?
too much Fe: damage to heart and liver
too little Fe: anaemia
too little Zn: growth failure, scaly skin, inflammation, reproductive failure, impaired immunity
too much Cu: damage to liver, discolouration of skin, hair, hyperactivity in children
