This project has focused on establishing a specific multipurpose labelling system via the modification of D-( + )-biotin in use with (strept)avidin proteins for purification and isolation. Two biotin analogues; 2-azidobiotin and 2-propargylbiotin, have been synthesised, introducing an alkyne and azide group at the 2 position of the valeryl side chain of biotin respectively. Isothermal titration calorimetry studies showed that the biotin analogues had a reduced affinity (Kd= 1V10-9 M) for strept(avidin) proteins, when compared to biotin (Kd= ~10-15 M).