Tuberculosis is a bacterial disease that causes the deaths of over1 million people a year annually. These bacteria survive within white blood cells and the acquisition of the iron they

need for survival can be difficult. The bacteria use two types of siderophore to aid the acquisition of iron. Shown below are compound 4 which is an example of one type and compound 5 is an example of the second type used by these bacteria. a) Based on what you know about siderophores, identify thechelating group present in compound 4. b) Identify the denticity of compound 4 and by considering the most favoured coordination geometry of Fe(lII), state how many molecules of compound 4 are required to fully coordinate one Fe(lll) ion? c) Predict the charge of the complex formed by compound 4and Fe(llI) at pH 7, explaining how you came to your answer. Note, the approximate pK, values for 4 are around 2.5 for-COOH, between 9 and 10 for -NH3* and between 6 and 7for -CON(OH). marks)d) Comment on the significance of each of the following points with respect to compound 4, in terms of its efficacy as a siderophore. i. The stability constant for this ligand with Fe(llI) is 1031.4.You should also suggest whether the value is high or low,and explain why this might be the case. ii. E° (Fe+| Fe2+) for the complex is -0.55 V e) Compound 5 is a membrane bound siderophore and aids transport of the Fe* into the cell, where it is reduced to Fe*.It is believed that siderophore 4 transports iron to siderophore 5 in the bacteria which cause tuberculosis. By considering the structure of compound 5, and the following data, suggest how compound 5 aids transport of iron into the bacterial cell. Stability constant for compound 5 with Fe(III) is 1022.7 E° (Fe*| Fe*) for the complex is -0.30 V.