Interaction of porphyrins with concanavalin a and pea lectin

Bhanu, K. ; Komath, S. S. ; Maiya, B. G. ; Swamy, M. J. ; Bhanu, Kancheenadham ; Komath, Sneha Sudha ; Maiya, Bhaskar G. ; Swamy, Musti J. (1997) Interaction of porphyrins with concanavalin a and pea lectin Current Science, 73 (7). pp. 598-602. ISSN 0011-3981

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Currently porphyrins are used as photosensitizers in photodynamic therapy for the treatment of cancer. However, this approach suffers due to the inability of many porphyrin-based drugs to accumulate preferentially in tumours. In view of this, we considered if the carbohydrate-binding proteins, lectins, which preferentially recognize malignant cells, could be used for the targeting of porphyrins to tumour cells. In the present study, we have investigated the interaction of a free base porphyrin, meso-tetrasulphonatophenylporphyrin and the corresponding metal derivative, meso-zinc-tetrasulphonatophenylporphyrin with two legume lectins, concanavalin A and pea (Pisum sativum) lectin. Each lectin subunit was found to bind one porphyrin molecule and the association constant, Ka, estimated from absorption and fluorescence titrations at room temperature (28 +/- 1 degree centigrade) was in the range of 1.2 X 10 to the power of 4 M to the power of -1 to 6.3 X 10 to the power of 4 M to the power of -1. Both free lectin and lectin saturated with the specific saccharide were found to bind the porphyrin with comparable binding strength, indicating that porphyrin binding takes place at a site different from the sugar-binding site. These results indicate that lectins may potentially serve as drug-delivery agents for porphyrin sensitizers in photodynamic therapy.

Item Type:Article
Source:Copyright of this article belongs to Current Science Association.
Keywords:Porphyrins; Concanavalin A; Peas; Lectins
ID Code:95880
Deposited On:07 Dec 2012 09:35
Last Modified:19 May 2016 08:26

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