diff --git a/docs/release/v2.3_series.rst b/docs/release/v2.3_series.rst
index 8b3f3e345..edea3e358 100644
--- a/docs/release/v2.3_series.rst
+++ b/docs/release/v2.3_series.rst
@@ -10,6 +10,8 @@ ProDy 2.3 Series
 **Bug Fixes and Improvements**:
 
 * use of 4-char hybrid36 (residue version) for biomol segnames 
+* remove pfam tests
+* remove python 3.5 support
 
 2.3.0 (Nov 12, 2022)
 ------------------------------------------------------------------------------
diff --git a/prody/__init__.py b/prody/__init__.py
index 19cab3abe..9c493a62a 100644
--- a/prody/__init__.py
+++ b/prody/__init__.py
@@ -11,8 +11,8 @@
     sys.exit()
 
 if sys.version_info[0] == 3:
-    if sys.version_info[1] < 4:
-        sys.stderr.write('Python 3.4 and older is not supported\n')
+    if sys.version_info[1] < 6:
+        sys.stderr.write('Python 3.5 and older is not supported\n')
         sys.exit()
 
 try:
diff --git a/pyproject.toml b/pyproject.toml
deleted file mode 100644
index 1a12ef550..000000000
--- a/pyproject.toml
+++ /dev/null
@@ -1,2 +0,0 @@
-[build-system]
-requires = ["setuptools", "wheel", "numpy>=1.10", "pyparsing", "biopython<=1.76", "scipy"]