Journal
BRAZILIAN JOURNAL OF MEDICAL AND BIOLOGICAL RESEARCH
Volume 55, Issue 1, Pages -Publisher
ASSOC BRAS DIVULG CIENTIFICA
DOI: 10.1590/1414-431X2022e12272
Keywords
Synthetic and endogenous protoporphyrin IX; Aggregation; Bovine serum albumin; Binding
Categories
Funding
- Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq) [304863/2017-3]
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2019/25054-2]
- Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior -Brasil (CAPES) [001]
Ask authors/readers for more resources
The interaction between synthetic protoporphyrin IX and protoporphyrin IX extracted from Harderian glands of ssp Rattus novergicus albinus rats with bovine serum albumin was studied. The aggregation and binding properties of protoporphyrin IX were found to be influenced by pH. Protoporphyrin IX has potential applications as a fluorescence probe and photosensitizer.
The study of the interaction of synthetic protoporphyrin IX (PpIXs) and protoporphyrin IX extracted from Harderian glands of ssp Rattus novergicus albinus rats (PpIXe) with bovine serum albumin (BSA) was conducted in water at pH 7.3 and pH 4.5 by optical absorption and fluorescence spectroscopies. PpIXs is present as H- and J-aggregates in equilibrium with themselves and with monomers. The PpIXs charge is 2(-) at pH 7.3 and 1(-) at pH 4.5. This increases its aggregation at pH 4.5 and shifts the equilibrium in favor of J-aggregates. In spite of electrostatic attraction at pH 4.5, where BSA is positive, the binding constant (K-b) of PpIXs to BSA is 20% less than that at pH 7.3, where BSA is negative. This occurs because higher aggregation of PpIXs at pH 4.5 reduces the observed K-b value. At both pHs, water-soluble PpIXe exists in the monomeric form with the charge of 1(-) and its K-b exceeds that of PpIXs. At pH 4.5, its K-b is 12 times higher than that at pH 7.3 due to electrostatic attraction between the positively charged BSA and the negatively charged PpIXe. The higher probability of PpIXe binding to BSA makes PpIXe more promising as a fluorescence probe for fluorescence diagnostics and as a photosensitizer for photodynamic therapy. The existence of PpIXe in the monomeric form can explain its faster cell internalization. Aggregation reduces quantum yields and lifetimes of the PpIXs excited states, which explains higher phototoxicity of PpIXe toward malignant cells compared with PpIXs.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available