Albumin domain II mutant with high bilirubin binding affinity has a great potential as serum bilirubin excretion enhancer for hyperbilirubinemia treatment

Truncated domains of human serum albumin improves the binding efficiency of uremic toxins: A surface plasmon resonance and computational approach

Albumin binding is the major cause for the toxicity of protein bound uremic toxins (PBUTs) in uremic patients. Albumin binding property is exploited to address this issue, as some of the extracorporeal dialysis systems use albumin as dialysate. In this line, a detailed study about binding of PBUTs to human serum albumin (HSA) and its domains gives valuable information. The focus of this work emphasizes the mechanism of binding of HSA and its domains with a few selected PBUTs such as hippuric acid (HA), indole acetic acid (IAA) and melatonin. The HSA domains (D2, D3 and D2-3) were expressed in Pichia pastoris and purified by using Albupure matrix. The binding of the expressed domains and HSA, with PBUTs, was measured using surface plasmon resonance and analyzed. All the three domains have significant affinity towards PBUTs, while D3 had greater affinity for all the three selected PBUTs. Docking studies showed that the basic amino acid, lysine, was forming hydrogen bond with PUBTs inorder to stabile these complex. This study would be having therapeutic importance for preparing the extracorporeal dialysis systems, in combination of different domains of HSA to remove the PBUTs.

S-Nitrosated alpha-1-acid glycoprotein exhibits antibacterial activity against multidrug-resistant bacteria strains and synergistically enhances the effect of antibiotics

Alpha-1-acid glycoprotein (AGP) is a major acute-phase protein. Biosynthesis of AGP increases markedly during inflammation and infection, similar to nitric oxide (NO) biosynthesis. AGP variant A (AGP) contains a reduced cysteine (Cys149). Previously, we reported that S-nitrosated AGP (SNO-AGP) synthesized by reaction with a NO donor, possessed very strong broad-spectrum antimicrobial activity (IC50 = 10-9-10-6 M). In this study, using a cecal ligation and puncture animal model, we confirmed that AGP can be endogenously S-nitrosated during infection. Furthermore, we examined the antibacterial property of SNO-AGP against multidrug-resistant Klebsiella pneumoniae and Pseudomonas aeruginosa to investigate the involvement of SNO-AGP in the host defense system. Our results showed that SNO-AGP could inhibit multidrug efflux pump, AcrAB-TolC, a major contributor to bacterial multidrug resistance. In addition, SNO-AGP decreased biofilm formation and ATP level in bacteria, indicating that SNO-AGP can revert drug resistance. It was also noteworthy that SNO-AGP showed synergistic effects with the existing antibiotics (oxacillin, imipenem, norfloxacin, erythromycin, and tetracycline). In conclusion, SNO-AGP participated in the host defense system and has potential as a novel agent for single or combination antimicrobial therapy.

Unraveling the Stability of Plasma Proteins upon Interaction of Synthesized Androstenedione and Its Derivatives-A Biophysical and Computational Approach

4-Androstene-3-17-dione (4A), also known as androstenedione, is the key intermediate of steroid metabolism. 5β-Androstane-3-17-dione (5A) and (+)-6-methyl-5β-androstane-3-17-dione (6M) are the steroid derivatives of androstenedione. The interactions of androstenedione and its derivatives with plasma proteins are important in understanding the distribution and bioavailability of these molecules. In our present study, we have studied the binding affinity of androstenedione and its derivatives with plasma proteins such as human serum albumin (HSA) and α1-acid glycoprotein (AGP). Our results showed that the 4A, 5A, and 6M steroid molecules can form stable complexes with HSA and AGP. The affinity of the studied steroid molecules with HSA is high compared to that with AGP, and the binding constants obtained for 4A, 5A, and 6M with HSA are 5.3 ± 2 × 10⁴, 5.3 ± 1 × 10⁴, and 9.5 ± 0.2 × 10⁴ M^-1, respectively. Further, binding sites of these steroid molecules in HSA are identified using molecular displacement and docking studies: it is found that 4A and 5A bind to domain III while 6M binds to domain II of HSA. Furthermore, the circular dichroism data revealed that there is a partial unfolding of the protein while interacting with androstenedione and its derivatives. Also, molecular dynamics simulations were carried out for HSA-androstenedione and its derivative complexes to understand their stability; hence, these results yielded that HSA-androstenedione and its derivative complexes were stabilized after 15 ns and maintained their stable structures.

Comparison of Posttranslational Modification and the Functional Impairment of Human Serum Albumin in Commercial Preparations

On account of its long circulating half-life, human serum albumin (HSA) is susceptible to posttranslational modifications that can alter its functions. Here, we comprehensively compared the degree of posttranslational modifications with the functional impairment of HSA derived from 5 different commercially available albumin preparations and clarified their relationships. We used electrospray ionization-time of flight mass spectrometry to evaluate the degree of posttranslational modification of the entire HSA molecule that was associated with disease development and found that the fraction of Cys34-cysteinylated HSA (Cys-Cys34-HSA), a major form of oxidative modification, varied substantially among the albumin preparations. Meanwhile, no remarkable difference was found in the degree of glycated or N-terminal truncated HSA among the preparations tested. The nonosmotic pressure maintenance functions of HSA, such as its antioxidative and ligand-binding activities significantly differed among the preparations. Interestingly, the alternations of these functions showed a significantly negative correlation only with the Cys-Cys34-HSA fraction. These findings suggest that the Cys-Cys34-HSA fraction, as estimated by electrospray ionization-time of flight mass spectrometry can be used as a predictive marker for the functional impairment of albumin preparations and that it would be preferable to use albumin preparations with higher contents of functionally effective albumin that correspond to a lower degree of cysteinylation of Cys34 in clinical practice.

Therapeutic effects of probiotics on neonatal jaundice

Objective:

To evaluate the therapeutic effects of probiotics on neonatal jaundice and the safety.

Methods:

Sixty-eight neonates with jaundice were divided into a control group and a treatment group (n=34) randomly, and treated by blue light phototherapy and that in combination with probiotics. The serum bilirubin levels were detected before and 1, 4, 7 days after treatment. The time when therapy showed effects and jaundice faded, clinical outcomes as well as adverse reactions were recorded. The categorical data were expressed as (±s) and compared by t test. The numerical data were expressed as (case, %) and compared by χ² test. P<0.05 was considered statistically significant.

Results:

Serum bilirubin levels of the two groups were similar before treatment (P>0.05). The levels significantly decreased 1, 4 and 7 days after treatment (P<0.05), but there was no significant inter-group difference on the post-treatment 1st day (P>0.05). The treatment group underwent more significant decreases on the 4th and 7th days than the control group did (P=0.002, 0.001). In the treatment group, the therapy exerted effects on (1.0±0.5) d and jaundice faded on (3.8±1.7) d, which were (2.6±0.6) d and (5.3±2.1) d respectively in the control group (P=0.001, 0.002). The effective rate of the treatment group significantly exceeded that of the control group (P=0.002). There were no obvious adverse reactions in either group.

Conclusions:

Probiotics lowered the serum bilirubin levels of neonates with jaundice rapidly, safely and significantly, and accelerated jaundice fading as well. This method is worthy of application in clinical practice.

Potential Use of Biological Proteins for Liver Failure Therapy

Biological proteins have unlimited potential for use as pharmaceutical products due to their various biological activities, which include non-toxicity, biocompatibility, and biodegradability. Recent scientific advances allow for the development of novel innovative protein-based products that draw on the quality of their innate biological activities. Some of them hold promising potential for novel therapeutic agents/devices for addressing hepatic diseases such as hepatitis, fibrosis, and hepatocarcinomas. This review attempts to provide an overview of the development of protein-based products that take advantage of their biological activity for medication, and discusses possibilities for the therapeutic potential of protein-based products produced through different approaches to specifically target the liver (or hepatic cells: hepatocytes, hepatic stellate cells, liver sinusoidal endothelial cells, and Kupffer cells) in the treatment of hepatic diseases.